I struggled with around 80% of this book, which felt a little like a showcase for all the interests of the author, which he wanted to write about and shoehorned into the narrative.

The story involves an extended family and friends group.

Sebastian is a schizophrenic who is being seen by Dr Martin Carr, who lives with his wife, Lizzie (also a psychologist) in London. Carr has 2 children - Charlie, biological son and Olivia, an adopted daughter. Olivia and Sebastian are twins but had not met until Olivia's birth mother arranges an ill-advised meeting at her home. The fallout from these relationships colour the end of the book.

The main part of the narrative is introducing those characters plus many others, whose names I cannot recall, who all seem to be in some form of crisis-either physical, mental or relationship-wise.

I got somewhat lost trying to remember who was married to who, what their problems were and where I'd met them first.

The part of the book that I really enjoyed was at the end when Sebastian and Olivia begin to forge a real relationship. I've no real idea what part a lot of the other characters played other than to pad out the narrative.

Not for me (except the last bit). But if you've enjoyed St Aubyn's other books you will probably enjoy this. The lives contained within it are certainly just as chaotic as Patrick Melrose's.

Thankyou to Netgalley and Random House for the advance review copy.

Edward St Aubyn returns with a follow-on to his 2021 novel Double Blind. I had not read that novel before reading this, and found Parallel Lines to be a great standalone novel in its own right. If you have read Double Blind you may get even more from it than I did. What did I get from Parallel Lines? Given it's from a writer of such stature as St Aubyn, you know immediately that the writing is going to be great - it is. The story is engaging, and I read it over in one sitting, totally engrossed by it's story.

Given it is a sequel, there is probably some duty on St Aubyn's part to give us updates on some of the characters from that first novel, so to me a few lines felt extraneous - but probably if read in sync with Double Blind it probably fits even tighter than I'm giving it credit for.

The best recommendation I can give is that it has made me go out and order Double Blind to finish the diptych in reverse.

Many thanks to the publishers and Netgalley for the ARC.

I absolutely loved this book. It follows on from, and we catch up with, the characters first introduced in Double Blind and you do need to read that book first to really get under the skin of what happens in this. Oh and before I forget, this book isn't the end for them either, or so it appears. I'm thinking probably trilogy rather than series, bit who knows how far the author will take them...
So, if you recall, at the end of the last book we had Sebastian meeting Olivia at a do where she is a guest and he a waiter. Unbeknown to them, they are related. To ice that cake, Olivia's adopted father Martin is Sebastian's psychotherapist.
This book picks them up 5 years later. Olivia is still with Francis who is still off on his rewilding escapades, and they are now parents to Noah. Sebastian has had a breakdown and is in hospital still under the care of Martin, and a nurse called Helio. Lucy is in treatment for her brain tumour, with boyfriend Hunter off seeking help for himself in an Italian Monastery, hosted by the abbott, Guido.
Although there is a lot going on with the supporting cast, the main focus is on Olivia and Sebastian and the two of them circling around each other. Whether they do meet properly, and how that impacts both of them, and their relationships with the other cast, especially with regards to medical ethics, I will have to leave for you to discover for yourself.
One of the things I love about this book, and its predecessor, is the way the author portrays Sebastian's fractured mind. His running commentary, his inward thoughts. All delivered in a wonderfully lyrical way and with such logic that actually had me rethinking quite a lot of my own thoughts and conceptions. I especially loved his interactions with certain other cast members, spoilers prevent me from going into detail though.
As with Double Blind, there are parts of this book that are a bit over my head. Intellectually speaking. But that doesn't really matter as I was able to just read through these parts and it didn't appear to mar my overall enjoyment of the book.
There were a few political moments and obviously covid was mentioned in dispatches but these were all in alignment with the characters and the time and setting.
And then there's the wit and humour which, happily, is right on my wavelength. Double Blind and this book are the only two books I have read by this author thus far but I have added the Patrick Melrose books to my ever growing TBR to keep me going until the next in this series is released.
My thanks go to the Publisher and Netgalley for the chance to read this book.

Parallel Lines has at its centre two characters: Olivia, a documentarian making a radio series about possible world-ending catastrophes, and Sebastian, a man in his fifth year of therapy with Olivia’s father, Dr. Martin Carr. It’s not giving too much away to reveal that the two lead characters, up to this point in their lives living ‘parallel’ but (almost) entirely separate existences, share a much deeper connection, which is revealed through the novel’s events.

Alongside these two, there’s quite the supporting cast for what is a relatively short novel. Notable significant others include Olivia’s friend Lucy and her techbro husband Hunter; Martin’s fellow psychologist wife and their biological son Francis (off eco-adventuring and contemplating philandering in South America); Father Guido, a friar who has been helping Hunter with a project; and Helio, an aspiring installation artist who Sebastian has met while institutionalised for a recent episode.

Despite the title, the book’s real interest is in bringing this eccentric cast of characters together, as memorably done towards its conclusion at a private dining event following an art exhibition. A little suspension of disbelief is required at the amount of coincidence required to achieve this (seemingly every character has some sort of tenuous connection to everyone else in the book), but it’s largely worthwhile, as this coming together is a standout of an otherwise somewhat uneven book.

Before going too far, I should admit one thing: I read this without realising it was a sequel to a book I hadn’t read. I don’t think I’m alone in this: much of the publicity avoids making this connection, presumably for fear of alienating newcomers, and at least one major review national newspaper’s review completely fails to mention it. In some senses I’m OK with this: it’s always interesting to review a book in this ‘pure’ fashion, to establish whether or not it stands alone (particularly when that’s how it’s being publicised).

On the other hand, I did feel slightly irritated (mainly at myself, for not having done the research). In this case, the existence of Double Blind explains away some of the bigger frustrations I had with Parallel Lines, namely that a large proportion of its extensive cast felt underused to the point where I was repeatedly left wondering why St Aubyn had bothered to include them. The answer is presumably largely fan-service of the ‘what are they up to now, I wonder?’ variety, for those who enjoyed the first book. From what I can gather, Olivia is the key character carried over from the first book, in that she remains central to this one rather than just one of many moving parts like the others who feature in both. But I could be wrong, of course, having not read Double Blind.

I don’t believe that Sebastian featured in that book (again, happy to be corrected on this!) and if we focus just on his story, Parallel Lines is much more satisfying as a standalone. In any case, he’s by some margin the most fully-realised character, the one with the most interesting storyline (around which everything else orbits, more or less successfully) and the spark for by far the best writing on display. This may be because, as with Melrose, in Sebastian we find St Aubyn diving again into the well of autobiography, which seems to be his richest seam. Sebastian is, of course, nothing much like Patrick. He’s endearing, somewhat wide-eyed at the world, and (at least by the book’s end) very much capable of charming and beguiling those around him. But like Patrick (and Edward) he has suffered abuse at the hand of his father (or fathers plural, in this case) and both suffered and caused suffering as a result.

His sections are the ones that fizz and spark, with his free associative language taking us on entertaining journeys (sometimes troubling ones, too, but always intriguing and betraying his character as a supremely intelligent mind boxed in by acquired social and mental blocks). There’s a childlike naivete to his thought process (hammered home a little in an interaction towards the conclusion) that enhances his charm even as we know it’s masking darkness.

The slight consequent issue is that most of the other characters fade into the background, including one of the key ones in Olivia, who I struggled to find especially interesting, and her family, who were perhaps purposefully annoying but not interestingly enough so. Hunter and Lucy may be more interesting to readers of the previous novel, but again I can’t comment. There are exceptions: Helio is likeable enough and works as a device for bringing Sebastian out of his shell as a character; and Father Guido is probably the other really interesting character in the book, though I didn’t feel we had quite enough time with him to fully explore his ‘man out of time and place’ role in the otherwise fairly culturally homogeneous grouping.

Ultimately, I found enough to enjoy in revisiting St Aubyn’s evident talents (particularly when they catch fire when voicing Sebastian) but didn’t feel this book entirely worked as a standalone. Sebastian’s development aside, plot points felt like they came and went, perhaps sometimes as some sort of resolution to threads begun in Double Blind and sometimes (as strongly hinted at the end) perhaps lighting the torchpaper for strands to be picked up in a future continuation. If St Aubyn is indeed reverting to this kind of multi-novel character development (and especially if Sebastian features prominently) then I’m fully on board with that, but in the meantime this felt in solus like a slight and only occasionally brilliant addition to his body of work.

(7.5/10)

Parallel Lines by Edward St Aubyn

Meet Sebastian,a young man undergoing long term psychiatric care. Then Olivia, journalist, documentary maker, her husband Francis,environmentalist,and their son Noah. They inhabit their own worlds; timelines in parallel,until circumstances and people cause a tilt to potential convergence.

This is a cerebral, intellectual book where in depth philosophical discussions, clever wordplay and reflections on life, elaborate a fairly simple story, though with equally challenging questions.

#docs.reading.room

I should begin by saying that i wish I'd read the book before this and I certainly shall read it eventually and just hope it makes sense to read in the wrong order. I have of course read the Melrose books and was hoping for something as good, which is totally unfair of me I know.

Anyway Ioved the set up idea of long lost twins reuniting after almost meeting each other before. It's a charming Shakespearean touch but quite horrific in real life especially when 'bio mum' wasn't really up to the job of any sort of parenting of two clever intellectually adept offspring, one with severe mental ill health. Sebastian is the twin who was accepted by birth mum which meant missed out on being adopted by the Carr family who adopted his female twin Olivia. Dr Carr then is eventually Sebastian's psychiatrist and there follows a tense few chapters where you can see the problems coming when Sebastian and Olivia find out.

It's clearly a novel of ideas but too obviously so at times, making characters hold forth about subjects at dinner parties or over drinks until you want to strangle them and beg them to move on. A very intellectual novel, but too much so for me because to me, once you saw the set up of the twins you so want to see what happens next in the narrative. The ecological issues and the criss crossing of all the other cultural and artistic issues with business and finance and stuff just made me want to skip parts of it and think 'Oh please, what are they on about? Tell me how Sebastian is doing now he's out of hospital!!' This is testament to St Aubyn's writing, and his ability to tell a story, but he's not hiding his extra interests with any subtlety and for me they pushed too much at the boundaries of my tolerance for clever clever writing which wasn't adding to the narrative. By the end perhaps, I might say it made sense to me.

It had won me over and I desperately wanted to know the next chapter of the story. Sebastian as a character is perfect at drawing you in with his naivety and vulnerability, added to his sort of uneducated but clever ideas which strike everyone he meets as being refreshing and charming. I found him very convincing in this respect and the ending has great charm and low key emotional impact. There must be more to follow.

In 2021 I read Edward St Aubyn's novel “Double Blind” and while elements of its were preposterous I concluded that I found it the most intellectually entertaining (or entertainingly intellectual) novel that I read in that year with its treatment of bio-diversity and extinction, epigenetics, brain mapping, venture capitalism, rewilding, the nature of consciousness, mind/brain dichotomy, psychoanalysis, mental heath and much more.

And this novel is a direct sequel to the first and while it can be read standalone – that is a little like saying that you can pick up a novel and read the second half only standalone – its neither what is intended I believe or certainly the right way to appreciate the novel and in fact will I think have a similar experience of finding yourself among a group of characters and plotlines already underway with limited backstory provided (the backstory of course being in the first book).

In particular the novel draws on a theme which particularly resonated for me in the first novel – twins – and in particular the separated at birth and both adopted pairing (with their Twelfth Night nod names) Olivia (adopted daughter of two psychoanalysts) and Sebastian (who is a patient of Olivia’s adopted father),

It follows both of the twins on their initially parallel paths (Olivia parenthood with her extremely unrealistically precocious young child Noah, Sebastian coming gradually to terms with managing his his schizophrenia – which thankfully also allows St Aubyn to gradually manage down his steam of connections chapters) and then on their inevitable intersection (which takes place at another of the slightly damp-squib set piece get togethers of all characters which seem to characterise this new series – but does feature the memorable both pre-imagined and double-meaning line “We don’t only have the same bio Mum we have the same psycho Dad”) – and perhaps more movingly through to the aftermath of the discovery of their connection in a closing section.

As well as having more character and feeling than the heavily exposition based first novel there is much more “art” and less “science” in this volume than the first – albeit one of the key themes of the novel is the artificial divide that has grown between the two (and between experimentation and experience, medicine and more holistic practices, and between disciplines in science).

The novel featuring for example the ballets of Crystal Pite and particularly “Statement” and her part of “Figures in Extinction”, Olafur Eliasson’s “Little Sun” (of course a deliberate science and art collaboration) and more than anything the light installations of James Turrell (including his installation at Houghton Hall).

Overall, while perhaps not up to the heights of “Double Blind” in isolation together it makes for an excellent series with the final part (and the penultimate sentence “To be Continued”) more than hinting at a welcome third volume in the series.

I enjoyed this book a lot as I found the characters and the writing interesting, funny and “thought-provoking(as one character observes, what can possibly be not thought-provoking?). The plot is not complex but the story kept me hooked. Martin is a psychiatrist and one of his patients is Sebastian, a strange, vulnerable young man. Sebastian is the most interesting character in the novel and I found him funny and engaging. He is undergoing therapy and has been in hospital and to him the world is a very odd place as his mind constantly makes all sorts of unusual associations between things.
Martin’s adopted daughter is Olivia and she has a slight and difficult relationship with her biological mother. I also found Olivia to be a sympathetic character.
The story really rotates around the relationship between these three characters though other related characters also appear and lend weight to the book.
The style of writing is fairly dense at times with long, complex sentences and a focus on ideas. It’s certainly challenging at times but I liked that.
This is the first book I’ve read by the author and it made me want to read more of his work.
Thanks to the publisher Jonathan Cape and Netgalley for an ARC in return for an honest review.

Of course authors evolve and move on but every time I see a new book by the gifted Edward St Aubyn I hark back to the unmatched and incredible Patrick Melrose series which as a lover of Simon Raven’s oeuvres I totally adored.

Of course this is humorous and beautifully written but the exploits of Sebastian and Olivia fail to grab me or even shock me to the extent his finest work did.

I enjoyed it and laughed throughout but I mourn the passing of Patrick Melrose and yearn for his return.

I haven’t read Double Blind, but after reading Parallel Lines, I will, and will reread Parallel Lines again.
The premise, while interesting, is a bit of a deus ex maccina.
When you get past it, which happens after reading the blurb and the first chapters, you get an engaging story about upbringing, psychology and human connection.
I liked how Olivia’s and Sebastian’s inner thoughts were written.

Absolutely loved this one. It's a really strong family story, with witty dialogue, contemporary issues, and astute social observations that, a few times, made me laugh out loud. I found the first chapter difficult to navigate but once I got my head around the style, he became my favourite character and I loved how St Aubyn depicted the families in the book. A great novel that I'll recommend to friends.

Parallel Lines by Edward St Aubyn is set to be published by Jonathan Cape on 1st May 2025.

Parallel Lines follows Sebastian, a mental health patient under the supervision of Dr. Carr, and Olivia, a mum coping with her young son's dinosaur obsession while she makes a podcast about the different ways we could become extinct in the near future. These two seemingly unconnected figures discover that they are biological twins, having been adopted at 18 months and birth respectively. Things are made even more complicated by the fact that Dr. Carr, Martin, is Olivia's adopted father.

The novel was recommended to me because I had enjoyed Séan Hewitt's masterful Open, Heaven and I can somewhat see the reasoning behind this, even if St Aubyn’s novel never quite reaches Hewitt's lofty, poetic heights.

I have never read any of St Aubyn’s previous work, although the Patrick Melrose series is one I was tangentially aware of due to its popularity. I have to say that he writes in an odd, philosophical way here that doesn't always quite ring true for his characters and I think in this case focusing so often on such pretty prose and philosophical thoughts comes at the detriment of plot and character. It came across more like Samantha Harvey's Orbital and Separate Rooms by Pier Vittorio Tondelli in this regard than Open, Heaven, both of which disappointed me (especially in comparison to Hewitt's work).

I have to say I struggled a lot with the opening chapters of the novel, and it wasn't until around the halfway mark that St Aubyn really hits his stride. The strongest sections are those from Noah's perspective, as St Aubyn expertly captures his voice as an underestimated, intelligent child. St Aubyn writes strongly on interconnectedness and the values we place on each other, however, and I left the book in a much more positive position than I had thought I would.

I found out by chance when I was about halfway through Parallel Lines, that it was a standalone sequel to Double Blind. It didn’t really matter, but I did find I had to keep checking who was who in the earlier part of the book, probably because they had all been more thoroughly introduced in the earlier novel. There were times when I found the story too wordy, too keen on examining interesting ideas in a way that felt a bit weighty for the narrative. The fragile but brilliant character of Sebastian, however, was a real delight and his connection, (or rather, reconnection),, with Olivia, his “Bio sis” was, for me, the highlight of the novel

While the whole concept and packaging were highly engaging, I felt I needed to have read the first book “Double Blind "to fully appreciate the plot. For this reason, I couldn't quite get to grips with some of the characters who appeared somewhat randomly. Having said that I warmed to the character Sebastian and his unconscious outbursts as he suffered another breakdown. There was a sense of humour and realism with his development, Olivia also held my interest as we delve into her mindset having realised that she is Sebastian’s twin sister and now his therapist's adopted daughter. We witness how the two have developed according to their environment.

I enjoyed St Aubyn’s style of writing, and he is evidently extremely talented which is why I will read the first book and revisit this one again.

Thank you NetGalley for the opportunity to read this ahead of publication.

This is a rather challenging read and one I think I need to revisit, I loved the cover; it’s dramatic, intriguing and caught my attention. The blurb sounded interesting, something if a story for our times. I wasn’t aware that this is a sequel to an earlier book and I think it would be better to read that first. I intend to read Double Blind and reread Parallel Lines.

I found I didn’t know who was who or how they connected, at first. Being dropped into a stream of consciousness narrative early on was a little testing, but pulling it apart, there’s a lot of humour and once I went with the flow it felt entirely right for the situation; the midst of a schizophrenic breakdown. I’ve found it difficult to fully understand what’s going on and why. The relationships aren’t entirely clear, or seem strangely contrived and ultimately, it’s all a means to an end. But the journey is tough and the only thing that kept me reading was the power of the writing. It has elegance and strength. There doesn’t seem to be a spare word and I feel I’ve missed a trick in not getting to grips with it fully. I’ll read the first book and revisit this title, better informed to appraise it with a fuller understanding. In the meantime, because of the complexity and writing, I’m giving it 4*.
My thanks to the publisher and Netgalley for an early review copy.

Unreadable. As it is pdf it is impossible to adjust the font size in the Net Galley app so too small to read

It wasn’t until I was mid-way through this novel that I realised it is a sequel, and that might explain why I had felt that some characters had been almost parachuted into the plot. Although I wish that I had read the first book before starting “Parallel Lines”, I was enjoying it enough to continue reading. Much of the novel is almost in a “stream of consciousness” style which worked well for me, successfully helping to explain various characters’ attitudes and behaviours. There are some fairly lengthy considerations of contemporary social issues amongst the otherwise fairly fast-moving plot. I am now keen to read the earlier book, “Double Blind”, and shall be looking out for a third in the series, if and when one is published.

The first chapter almost put me off. But I was glad I persevered as the next few chapters fairly swept me along. It became sharp, clever and very current. Sadly though by just over half-way/two-thirds through I lost interest in the characters and just found the whole thing somehow 'excessive'. It became a bit tedious and overwrought. In fairness however, this was the first Edward St. Aubyn novel I had read and looking at some other reviews, perhaps I should not have started with this one. Special thank you to Vintage Books and NetGalley for a no obligation digital advance review copy.

This is actually a sequel to a 2020 novel "Double Blind." Whilst "Parallel Lines" can be read as a stand alone the narrative and the characters connections might have made a lot more sense to me sooner had I known this. The novel starts with Sebastian, having a schizophrenic break down in an institution with a big stream of his consciousness dumped on the reader, with some dark but witty elements. It's a bit disconcerting for the reader as it must be for poor Sebastian. His "psycho dad" ( psychiatrist) just happens (rather unbelievably) to be the adoptive father of his estranged twin sibling, Olivia - a huge conflict of interest that isn't explored. The story follows how Olivia and Sebastian eventually connect and Olivia's story is much more conventionally recounted. Stick with this book and it will reward you. I found it really interesting and in retrospect really liked how the first few chapters challenged me.

Parallel lines are a bad premise for a novel. Fiction comes into being when characters crash into each other with unexpected results. If people stay neatly travelling on their own parallel lines, you don't have a novel—you have an episode of Norwegian slow TV.

Fortunately, Edward St Aubyn preserves the parallel lines only for the first half of the book, before ignoring the title of his novel and making those lines crisscross and intersect. This is a novel of multiple characters and different threads, but the most interesting collision is between Sebastian and Olivia, twins who were separated at birth and had never met before (except at a party a few years earlier, when they chatted briefly without realising they were siblings).

Olivia was adopted at birth by Martin and Lizzie Carr, who are more or less the ideal parents: as professional psychoanalysts, they are emotionally aware and supportive, as well as being affluent enough to give her a good start in life. She goes on to become a researcher at Oxford and later a BBC radio presenter. Her twin brother, Sebastian, on the other hand, stayed with his birth parents—an abusive father and ineffective mother—before later being adopted by a couple who seemed not to be much better. He experiences severe mental illness and is in a Suicide Observation Room when we first meet him.

As it turns out, Sebastian's psychoanalyst just happens to be Martin Carr, Olivia's father. This is revealed quite early in the book, so I don't consider it a spoiler. In fact, it was the one part of the story that I found difficult to accept. I know people in this profession, and they've told me that having a personal connection to a patient is a serious ethical breach. Martin is presented in the book as a kind, caring and professional man, a good father and a good analyst, so I find it extraordinary that he would allow this breach to go on for years without simply referring Sebastian to a colleague.

But if you can accept that, it does make for a delicious premise. When Olivia and Sebastian finally meet, Martin must feign ignorance as he talks to each of them in turn. How long will it be before they discover that they share not just the same "Bio Mum" but also the same "Psycho Dad"?

The answer comes towards the back end of the book, in an extended chapter in which we see all of the main characters preparing to attend the same gallery opening in central London. St Aubyn does a great job of stretching this part out, making good use of the large supporting cast to keep the tension going for as long as possible, before finally those parallel lines intersect.

Along the way, we get some beautiful writing and fascinating dialogue. The characters' conversations are far more witty and insightful than any I've heard even when people are performing at dinner parties, let alone in the mundane domestic settings where most of the conversations take place. Here's Martin, for example, speaking about the politics of resentment:

"The politician who knows how to stir it up will always win—making people proud of what they used to be ashamed of is such an intoxicating alchemy."

There are loads of nuggets like that throughout the book. I'm not sure if people really talk that way—even Olivia's five-year-old son Noah is a budding intellectual—but it's wonderful to read.

The early sections with Sebastian are a brilliant and utterly convincing insight into the mind of a person who is constantly free associating, his thoughts jumping from topic to topic at lightning speed, connected by obscure but strangely logical lateral thinking. His first spoken words in the novel would be easy to see as unhinged ravings:

"By that fat cow! .... We've upgraded you from a classic Having room to one of our superior Being rooms ... Give it a rest, me old son ... I don't want to be radicalised."

But these outbursts take place several pages apart, and St Aubyn also takes us through Sebastian's intervening thought processes, revealing a mind that is making creative associations which he just can't control. As the book progresses, he begins to get more control over his thoughts and words, but he still has a tendency to spin from one thought to the next in unusual ways, sometimes to his advantage and sometimes not. It's a sensitive portrait of mental illness that makes Sebastian into a very interesting and surprising character.

Large themes are strewn throughout the book, explored both through the characters' erudite conversations and through aspects of the plot. Since there are two psychoanalysts and one patient at the heart of the novel, the functioning of the human mind is central, but there's also the role of religion, the looming threat of climate change and species extinction, the nature and extent of compassion, and more.

Light also plays a major role in the novel. The gallery opening at which all the parallel lines cross is an exhibit of light art—installations that use light in creative ways to challenge the viewers' perceptions. One of the hospital nurses, who later becomes Sebastian's friend and invites him to the opening, is also a light artist, and another minor character, Hunter, is a tech billionaire who wants to install pieces of light art on his expansive property. I haven't quite thought through the symbolism of it, but I suppose it's about the interconnectedness of the characters, the way they're all groping towards a light of understanding that, as in one of the main art pieces, was "there all along", even in what seems like darkness.

So what happens when those parallel lines do intersect? Not as much as I'd hoped. I won't spoil it by giving details because this really is the climax of the novel, but I thought St Aubyn could have made more of the fallout from the gallery opening at which all of the characters meet and Martin's secret comes out. The ending felt satisfying on some levels but incomplete on others, with the central conflict only briefly explored and multiple loose ends left hanging with the minor characters.

After finishing the book and reading up about it online, I realised that this novel is part of a larger series. It's a sequel to Double Blind, which I haven't read, and although I don't think there are more books officially lined up, the ending strongly suggests to me that there will be. The author's previous Patrick Melrose series spanned five novels over the course of a decade, so I suspect this will be a similar multi-part series.

That explains the ending that left me wanting more, as well as the multiple plot lines that were introduced but didn't really go anywhere. Some, I now realise, are continuations of storylines from Double Blind, and others, I imagine, will be more fully developed in the next installment. So although Parallel Lines does have a lot to offer as a standalone novel, I think you'd probably get more from it if you read it as part of the whole series.