I love when books involve the characters writing to each other whether it’s emails, letters or just little notes. So when I heard about a book which was solely told by letters I was excited to read it.

E lives in a house deep under the sea and is very isolated until she starts writing letters with Henerey as they work together to solve a mystery. E’s sister and Henerey’s brother start a correspondence to figure out what happened to their siblings.

I struggled a little at the start because of it only being letters you miss out on the more descriptive details and conversations that usually help with the world building. I think starting with a brief summary of why they are underwater and where exactly the people live would have been helpful.
Once I figured all of that out and the mysteries started I was hooked. I couldn’t wait to get to the end to find out what happened. It was great seeing how the relationships developed between each of the characters, and their reactions to reading the other letters. The author found clever ways to share conversations while still being in letter form which really helped to further the story.
Overall I enjoyed this book a lot once I got used to the writing style and I can’t wait to read the next one!

This was very endearing, whimsical and cosy, but ultimately it was just... Nice.

I really enjoyed the slightly formal epistolary style, and the sense of humour, but advertising this as a romance feels a little misleading.

I thought E and Henerey were supposed to be the main romantic couple, but truthfully, Sophy and Vyerin had more chemistry, despite being a queer woman and gay man.

There was also very little variation between the 4 main character's writing style, and the timeline was a little confusing. I do think the epistolary style works better with fewer points of view.

I wish there was more background information on so many things! I wanted to know more about the Deep House, about this world in general, as it sounded amazing, but was only explored on a very shallow level.

The mystery was a little disappointing too, because there was such a long build up to it, and I was let down by the ending.

My favourite thing was probably how big a part mental health plays here, mainly anxiety, some agoraphobia. I definitely liked how E and Henerey seemed to have found another person to connect with, who understood their struggles.

This will work for people after a cosy, easy little read about nothing but academic vibes with a touch of formal humour. Just don't expect any romance or plot.

Thank you Netgalley and Orbit Books for giving me the chance to read an ARC of this novel in exchange for am honest review.

A Letter to the Luminous Deep is an epistolary sci-fi/fantasy novel in which two of the main characters investigate the disappearance of their siblings by sorting through their letters to each other, as well as their own correspondence. It is a love story that develops on paper, alongside a mystery that spans timelines (although only about a year apart).

I'm a little divided on this one!

Let's start with what I really enjoyed. I was drawn to the book by its stunning cover (one of my favourite covers I've ever seen) and the intriguing premise. While the first part of the book felt quite slow, the last third of it was full of mystery and the intrigue kept growing! I wanted to know more about the mysterious Structure everyone kept talking about, and about the unusual creatures and patterns the main characters noticed around them. The last 25% of the novel took a rather unexpected turn, which I really liked as it took the story in a very interesting direction. I was also really impressed by the author's ability to create such a detailed world and describe it purely through letters, scientific journals and occasional interviews to characters! The deep-sea descriptions were breath-taking and I loved all the details about the creatures inhabiting this world.

Now onto what didn't convince me. The prose was extremely flowery and wordy, especially in the first half of the book! I found it quite distracting and it made reading the story much less smooth. This also slowed down the pacing quite a bit, in my opinion, so much so that I almost stopped reading after about 25%. I'm now glad I continued, but I wish the pacing had been different and supported what is otherwise a novel, interesting story!

This said, I will be getting the sequel next year as I'm really curious to find out what happened to the characters! The cliffhanger at the end of the story definitely left me wanting more. I also have lots of questions about what's to come, including what style it will be written in... as I think all the past correspondence has been explored, so there will have to be a new mean of story-telling?

★★★★.25

Dive into the whimsical depths of Sylvie Cathrall’s enchanting debut, "A Letter to the Luminous Deep," and prepare to be swept away on a magical underwater adventure!

Picture this: a reclusive soul named E. Cidnosin, tucked away in her cosy underwater abode, stumbles upon a breath taking sight outside her window. What follows is a delightful exchange of letters with the esteemed scholar, Henerey Clel. But these aren't just any letters—they're filled with scholarly musings, budding romance, and the promise of unravelling mysteries lurking beneath the waves.

As the story unfolds, tragedy strikes, and both E. and Henerey vanish, leaving behind a trail of letters, sketches, and field notes. Enter Sophy and Vyerin, the intrepid siblings left behind to solve the mystery of their disappearance. With each letter they pore over, they uncover secrets and revelations that could change their world forever.

One of the most captivating aspects of 'A Letter to the Luminous Deep' is its unconventional epistolary format. Through a series of letters exchanged between the characters, readers are drawn into a world where communication takes on a whimsical charm of its own. Each letter is a window into the characters' hearts and minds, revealing their deepest thoughts, fears, and desires in a manner that feels intimate and profoundly engaging. This unique storytelling technique not only immerses readers in the characters' lives but also adds layers of mystery and intrigue to the narrative, keeping them eagerly turning pages to uncover the secrets hidden within each correspondence.

But what truly sets "A Letter to the Luminous Deep" apart is its richly imagined world, where light academia meets magic in the most delightful of ways. From the cosy confines of Deep House to the vast expanse of the open sea, Cathrall paints a vivid tapestry of underwater life that will leave you utterly entranced.

And let's talk about the characters—each one is a gem, brimming with personality and charm. From E.'s endearing quirks to Henerey's scholarly wit, you'll find yourself falling in love with them all over again with every turn of the page. The novel offers a profound and authentic portrayal of mental health, particularly OCD, resonating deeply with readers as the author herself navigates life with OCD.

But perhaps the most magical aspect of this book is its heartfelt exploration of love, loss, and the power of connection. Through Cathrall's elegant prose, you'll be transported to a world where words have the power to heal, to comfort, and to forge bonds that transcend time and space.
While some may draw comparisons to 'Emily Wilde,' a whimsical tale in its own right, I found 'A Letter to the Luminous Deep' to be a true masterpiece. Where 'Emily Wilde' may have faltered at times, Sylvie Cathrall's debut shines brilliantly, weaving a spellbinding narrative filled with charm, mystery, and heart-warming romance. It's a story that lingers in the mind long after the final page is turned, leaving readers enchanted and eager for more.

So if you're in need of a whimsical escape from the ordinary, look no further than "A Letter to the Luminous Deep." It's a treasure trove of wonder and delight—a true masterpiece that will capture your heart and leave you longing for more.

Huge thanks to Orbit and NetGalley for providing me with an ARC of this stunning book! All opinions are my own.

I am not sure a fully epistolary format was the right choice for this book. It would have benefitted from a hybrid approach—think This Is How You Lose the Time War—especially as seen through Sophy’s eyes. And especially towards the end, where it read like the author was contorting herself in order to find solutions to remain consistent with the format.

We spend the majority of the book going back one year in time, before E. and Henerey go missing, piecing together the time before this sudden and mysterious disappearance. E.’s sister Sophy, and Henerey’s brother Vyerin start corresponding as a way of dealing with their grief, but this soon evolves into trying to understand what happened to their siblings.

I have two main issues with this book. Firstly, as stated above, I don’t think it was told in the best format. At its core, this is a mystery book—and an interesting one. The elements could have been handled better—the inciting incident was basically forgotten past the 10% mark. Still, I wanted to know what was going on, and the sections dedicated to Sophy’s research would have been best told in a regular narrative style. Through letters, I couldn’t be as immersed in her surroundings. They felt empty, even though the deep ocean was exactly what sold me on this book.

Then there’s the matter of everyone having the exact same voice—dashes notwithstanding. Arvist and Vincenebras are more boisterous than the rest of the cast, but not distinct enough. This format is especially harsh for show-don’t-tell, but it definitely could have used some work in that regard. It did very well at making sneaky references, but then wouldn’t just show us each main character’s personality, but rather have someone else point it out or have the character themselves say it.

So this all slowed me down. There was little to hold on to in the middle section. Some reveals were purposefully postponed simply due to narrative convenience, Sophy and Vyerin’s last proper conversation gets pushed back for entire sections because their siblings letters hadn’t caught up to that point in the story, etc.

Still, I loved the bits we got from the world—the architecture, sea creatures, vague mentions of how we all ended up in the water, etc. I am very curious about what comes next. And I deeply appreciate the casual representation of queer identities. I just wish I’d had more to sink my teeth into.

This book is for you if you enjoy:
- epistolary novels
- everything sea-related
- academia (leaning more towards light, though there are some elements of dark academia)
- reading about two people falling in love through letters
- cosy mysteries linked to the environment.

Many thanks to NetGalley, Sylvie Cathrall and Orbit for the chance to read and review this book.

A LETTER TO THE LUMINOUS DEEP is a dual timeline tale of love - romantic and familial - and the mystery of an unusual object spanning both times.

There are three main strands to the book - E. and Henery getting acquainted and looking into the strange sphere, what happened at the same time on Sophy's deep sea mission, and one year later as Sophy and Vyerin try to uncover the truth of what happened to their siblings while also processing their grief.

I liked that, while E. and Henery are in some ways the focus of the book, the second most important relationship is one of friendship. Sophy and Vyerin come together to process their grief, gradually forming a fierce friendship. It's so nice to see friendships getting page time in SFF as romantasy takes over and it feels like it's pushing other relationships out.

The mystery of the sphere is engaging, particularly as it's seen from three different sides thanks to the strands. Because Sophy and Vyerin's timeline follows them swapping letters including their siblings', it meant the revelations stacked up about the same time, allowing for a lot of "oh" moments close together.

The book is told entirely through letters and document extracts. It is a deliberately stylistic choice that leads to a few contrived feeling moments of "the reader needs this info about the characters so let's find a semi-believable way to get them to write about their appearance" etc. On the whole, though, it works.

I listened to this and was glad there were four narrators; Claire Morgan, Joshua Riley, Justin Avoth, and Kit Griffiths. I liked that each of the four main characters had their own narrator as it made it much easier to keep them apart, given the book is largely in first person. There are other characters' letters and papers read, and the four narrators do read them so they were slightly harder to follow as if I missed the "letter from X to Y, year" at the start, I had to rely solely on context.

I thought this was a standalone novel but I was 5% from the end and certainly wasn't near a conclusion. It turns out it's a duology, for which I'm glad because it ends with a lot of questions unanswered, given the modern day cast are gearing up for an expedition of their own.

This has not been a good year for my most anticipated ARCs, sadly. Here, we have another book I was immensely looking forward to, but when I started noticing myself grinding my teeth while reading, well…

Epistolary novels can be amazing, but they take a special kind of skill. Here, we have four letter writers who all write like they are Quirky, Highly Self Aware, and Prone to Unnecessary Overcapitalisation. All of them sound the exactly the same, and none of them sound like real people. It doesn’t help that most of the world-building is delivered by people writing large info dump paragraphs to each other in their letters (most of whom would have no reason to talk about these things with each other), so even the underwater setting couldn’t save this one.

Here’s to more luck with my next new release…

An immersive and magical underwater world and a tender love story.
I saw this book promoted as academics falling in love over letters and it was exactly that. It’s wholesome and a delight to read. The burn is slow as is the pace of this book but that went well with the whole feel of the story. There is a multitude of mysteries to unearth and at the end there is clearly more to be learned. As the underwater setting is so vast and unexplored the story could develop any which way.
Each character had a distinct voice and mental health/quirks were present, which I liked as they felt more relatable.
Overall a nice read.
Thank you to NetGalley and the publisher for an ARC. This is a voluntary review of my own thoughts.

Thankyou to NetGalley and Little, Brown Book Group UK | Orbit for a free ARC in exchange of an honest review!

This is my first book read that is fully comprised of letters and i have learnt that i adore this style!
It is lovely and whimsical and the way the book is split up into correspondences between multiple people really helped in keeping the pace up.
E and Henery are so cute and i wish we had more of those two however i found that i didn't dislike any of the different voices of correspondents and the side characters really add to the story. I loved the writing style- it was so descriptive and lyrical at times and the atmosphere felt kind of cosy.

Cant wait for the 2nd instalment!

5 Stars

I will be adding my review to my instagram page, closer to release day at www.instagram.com/readinglikeitsmyjob

The epistolary structure of the book is not for me, I am not usually one who enjoys this type of narrative—and yet, I could not help but be compelled by the world building and the characters. A Letter to the Luminous Deep is a beautiful, interesting story reminiscent of Emily Wilde’s Encyclopaedia of Faeries. The pacing is slow and there is not a lot of narrative progression, but overall a very enjoyable read.

Thank you to NetGalley and the publisher for providing an e-ARC copy of this book, in exchange for this honest review.

Thank you to NetGalley and the publisher for the advanced copy of this book!

I had the privilege of reading both the ebook and audiobook of this title, and both were great!

The audiobook performances really helped with the individual character voices over the letters, with each narrator giving a fantastic and unique performance.
The story is told through letters and records, it's an epistolary tale set in a mystical underwater fantasy world. The romance and the friendships were the absolute highlight for me, and I can't wait for the next instalment!

I admit, I expected something more!
The story itself is pleasant to follow, the characters are captivating, the worldbuilding intriguing and the epistolary structure a nice narrative gimmick.

The problem is that everything happens extremely slowly and practically nothing happens.
Furthermore, and this for me was the thing that ruined the reading the most is that the characters whose point of view we follow through the letters are absolutely indistinguishable from each other!

Cute but has, in my opinion, a lot of flaws!

4.5⭐️ A stunner of a book, this has all the magic and whimsy of Emily Wilde’s Encyclopaedia of Faeries but is a truly unique book with an unusual style that may not be for everyone but is certainly for me! I absolutely adored that this was an epistolary book- there’s just something so intimate and cosy about unraveling a story through personal correspondence and it makes for a book with personality. While this book explores themes of loss it remains low stakes, a soothing, cosy read to get lost in as you escape to the underwater world.

Exploring the light side of academia, I enjoyed piecing together the acquaintance turned friendship turned romance between E and Henery as well as the mystery surrounding what they discovered and what happened to them. The world the book was set in was crafted wonderfully, the society E inhabited feeling like a pseudo/alternate 19th Century due to the style of writing, the way the characters speak and the discussion of societal expectations that align with our Victorian/Edwardian time period.

I found the characters to be likeable, I could relate to E’s anxiety and the way she didn’t quite fit in and I found Henery to be just dreamy- a poetic, swoonworthy gentleman worthy of a place on among the pages of a historical romance!

I’m keeping everything crossed for a sequel because I simply MUST read more about Henery, E and their underwater adventures.

3.5 stars. I'm having a hard time writing a review about this one. On the one hand, this was really enjoyable with a decent plot, lovable characters and a very unique way of telling the story. On the other hand, I found this to be very slow with little to nothing happening. I didn't always mind the lack of pacing, but at times it was very hard for me to continue and to be concentrated. Still, in the end I found myself rating it 3.5 stars as I did enjoy it overall. I would recommend it!

𝓣𝓱𝓮𝓻𝓮 𝓪𝓻𝓮 𝓼𝓸 𝓶𝓪𝓷𝔂 𝓫𝓸𝓸𝓴𝓼 𝓪𝓷𝓭 𝓼𝓸 𝓶𝓪𝓷𝔂 𝓲𝓭𝓮𝓪𝓼 𝓲𝓷 𝓽𝓱𝓮 𝔀𝓸𝓻𝓵𝓭, 𝓪𝓷𝓭 𝓱𝓸𝔀 𝓬𝓪𝓷 𝓘 𝓱𝓸𝓹𝓮 𝓽𝓸 𝓾𝓷𝓭𝓮𝓻𝓼𝓽𝓪𝓷𝓭, 𝓵𝓮𝓪𝓻𝓷, 𝓸𝓻 𝓭𝓲𝓼𝓬𝓸𝓿𝓮𝓻 𝓮𝓿𝓮𝓷 𝓪 𝓯𝓻𝓪𝓬𝓽𝓲𝓸𝓷 𝓸𝓯 𝓽𝓱𝓮𝓼𝓮 𝔀𝓸𝓷𝓭𝓮𝓻𝓼 𝓲𝓷 𝓶𝔂 𝓼𝓱𝓸𝓻𝓽 𝓵𝓲𝓯𝓮?

𝑅𝑒𝓋𝒾𝑒𝓌: ☆ ☆ ☆ ☆ ☆

Thank you to Orbit UK and Netgalley for this e-arc. All thoughts are my own.

This is truly an original and ambitious book. It’s an epistolary fantasy, which was something very different and interesting for me. Cathrall successfully manages to balance the mystery, romance and timeline, to create a beautiful and tense story.

This is a dense and slow book, and I believe that you’re meant to savour it. Personally, it felt familiar to me, as I’ve spent a lot of time reading old letters and correspondence for my degree, and I enjoyed these little pieces that made up these mesmerising word. It was beautiful see the story unfold like this, and I genuinely felt like I was apart of the story, reading the letters alongside Sophy and Vyerin.

What I loved most about this book, was that the information is slowly teased out from the material, which includes the world building and history. I felt like the Cidnosin siblings whenever their mother forced them to pieces together a mystery, but I absolutely loved that. It kept my brain engaged and turning.

All of the characters are incredibly well written, with so much life breathed into them. My favourite was definitely E. of course. She was so relatable, in both the good and bad. E’s journey in these letters was so powerful, and her humour was brilliant. Her and Henerey’s relationship was absolutely adorable, and it’s my favourite type of romance; slow and full of emotional connection.

I had no idea that this was part of a series, and I now eagerly await book two so I can dive (pun intended) into this world again.

Title: A Letter To The Luminous Deep By Sylvie Cathrall

Release Date: April,25th 2024

⭐️⭐️⭐️⭐️Stars


Dive into the enchanting tale of "A Letter to the Luminous Deep," where reclusive E. and scholar Henerey Clel embark on a captivating correspondence after a mesmerizing discovery beneath the waves. As their letters blossom into something more, they delve into the mysteries of the underwater world together. But when disaster strikes and both vanish without a trace, it's left to E.'s sister Sophy and Henerey's brother Vyerin to piece together their story.

With letters, sketches, and field notes as their guide, they uncover a love story beyond imagination and unlock the secrets of their disappearance, changing life as they know it forever.

In "A Letter to the Luminous Deep" by Sylvie Cathrall, the unique narration style initially posed a challenge for me, as the story unfolds through exchanged letters by various characters. However, once I adjusted to this concept, I found it incredibly immersive and personal, allowing me to connect deeply with the characters' thoughts and emotions.

What struck me the most was the unexpected twist at the end, which left me hanging on the edge of my seat and eager for more. It came as a surprise to discover that this book is part of a series, but now I can't wait to dive into the next installment to uncover more mysteries and continue following the captivating journey of the characters.


Thank you to NetGalley, Orbit and Sylvie Cathrall for an advanced reader copy (ARC) in exchange for my honest review.

A Letter to the Luminous Deep is a slow-paced story that handle some real-life issues such as mental health, anxiety and even grief. I never read an epistolary novel before and both the title and the blurb made me curious to try, especially because it has a focus on the romance.

This is kind of a cozy fantasy with a romance set in a mythical underwater world that has Emily Wilde’s Encyclopedia of Faeries vibes since they touch academic endeavors. The epistolary format was not for me so I couldn’t enjoy this story fully which was a shame since I do love Victorian English vibes.

Overall, the concept is good, and it felt like a refreshing fantasy story, however I cannot say I’m a fan of the way it was written since I felt distracted at some points. The concept of the book is amazing and for fans of the writing style I’m sure it’ll be a delight, but it just didn’t work for me. I still enjoyed the story and I recommend it to those who want to explore different ways of diving into fantasy.

Thank you, NetGalley & the publisher, for approving me to read this arc and write this review.

Oh I love love loved this one! Told entirely in letters, we follow Sophy and Vy as they try to uncover the mystery of their respective siblings (E. and Henery) disappearance. Through these letters we see how shy Henery, and E. - a girl suffering from fairly intense OCD and anxiety, formed a friendship which later developed into a love.

I will say that this book is very slow paced and overly wordy in the way it's written. Everything is very heavily described and formal so I can see why some people wouldn't enjoy it but I would recommend persevering until at least the halfway mark as I found the latter part of this book was vastly better than the former.

Overall I liked the format (epistolary) but I would have liked to see the characters have more distinct voices in their letters because they all felt very interchangeable with one another which was a shame.

For me the two things that made me adore this book were firstly, the development of E and Henery's relationship and secondly, the mystery at the heart of the book. As someone who finds the sea terrifying, I felt like there was an almost creepy undertone which i really enjoyed.

Overall I look forward to seeing where this series goes and I will be posting a full review on my TikTok in the coming days.

A Letter to the Luminous Deep is unlike any other book I've read. I thought, with it being an epistolary novel, that I would feel some sort of detachment to the characters. After all, how much emotion can you truly get through letters... the answer, it seems, is a whole roller coaster ride's worth.

I suppose you could say there were 4 MC's in this book. We have E and Henerey, who start up a correspondence after E spots a marine animal she has never seen and writes to Henerey for his advice. And we also have Sophy and Vyerin, E & Henerey's siblings respectively, who start their own correspondence in the wake of their siblings disappearance. Cathrall does a truly amazing job of letting these characters shine through their letters, each having their own unique voice and ensuring that we love all of them equally. There's a risk to this though, a risk in keeping your characters interactions to letters, to even having their few meetings told through that lens, but it just works with this book and these characters. It allows the author to build a suspense, especially in how she layers the different letters through the book, and it absolutely adds to the emotional impact, rather than taking away from it.

I've read multi-media books before, but I have never read a book told solely through letters, poetry, academic papers etc. Cathrall uses all of these, not only to make us fall in love with her characters, but to build on her incredible world. It's so well built, and so unique, a world set in a place nearly completely covered by water, where the world used to float in the sky until it all came collapsing down and the societies we know today were created in the wake of it. The world is extensive, but thanks to the use of the letters it gets introduced to us naturally, through E and Henerey investigating her discovery and through Sophy and Vyerin trying to determine what happened to their siblings. It's a real mix of genre's; fantasy, romance, even dystopian in a way

The writing style definitely gave off some academic vibes. Sophy and Henerey were academics, E might as well have been one and Vyerin wasn't only because he found his own passion, but the way they write to each other carries an academic undertone, even when their letters shifted towards the more personal, there was still that academic vibe and that thirst for knowledge. I really enjoyed the mystery element to this story and how it was woven through. We start the book after E and Henerey's disappearance, which again was a unique way to tell the story, and the author uses them, and their investigation, to tell us the story of E and Henerey through letters and documents they sent to each other. This added another emotional element because, not only are we learning about them through their correspondence, but through the eyes of the two people who love them the most, Sophy and Vyerin.

Talking about love, A Letter to the Luminous Deep is set in a Queer norm world. In fact both Sophy and Vyerin are in F/F & M/M relationships. Though they may not be the shining stars of the book, at least romance wise, I enjoyed the insights we go into their relationships, especially Sophy because that it one we get to see blossom through the letters she writes to E. But now onto E and Henerey, who truly are the cutest two people ever. Their respect for each other starts almost immediately, with their feelings gradually progress through the book, showing in how their letters to each other change. E is someone who has struggled with a malady of the mind since she was a young girl, something that makes her overthink every action, decision, conversation. She feels she is nothing more than a hindrance to those she loves, so when she meets Henerey and he values her, her thoughts, her feelings, she starts to slowly but surely venture out of her shell. It truly was remarkable to, well read if not see, but you can almost feel E growing bolder letter by letter thanks to Henerey's validation of her feelings. It's such a heartwarming romance, no spice at all, but it wasn't needed because these two manage to fall in love over letters and one in person meeting.

If you can't tell already, I loved this book. Cathrall got the perfect balance between the fantasy and romantic aspects, and also gives us a mystery we are desperate to solve. It's a sweet story, but also one that feels a little malicious in parts, a teeny tiny bit scary and I loved how the author manages to keep us on our toes with nothing but letters and academic papers to whet our appetite. The book ends on a bit of a cliffhanger and I can't wait to get my hands on book two.

I loves the premise of the book but the style just wasnt for me.

The language is vedu poetic and flowery - at points this was beautiful but at other times far too much.

The story is ENTIRELY written in letters. Whilst a fan of the odd letter - I could not get into a book which eas entirely epistolary. I would not have requested had I known as this style of book just wasnt for me.

I have seen that other reviewers have said that the book picks up pace and that the last 25% of the book made it worth it but I couldnt get that far through. I would like to pick it up and try it again another time as the premise was really interesting.