Cover Image: Knock Knock (Detectives Lockhart and Green Book 1)

Knock Knock (Detectives Lockhart and Green Book 1)

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Member Reviews

The first in a new series called Lockhart and Green, I thought it may have been more appropriate being called Lockhart with a side of Green or even Lockhart and Smith!

Detective Dan Lockhart is our main character here. Ex army, wife missing presumed dead by all except himself and his mother. Dr Lexi Green is his psychologist. He is seeing her before work on his own time. 
When he investigates a couple of gruesome murders of women with the exact same methodology, he is one of the first convinced they have a serial killer on their hands even though the women have nothing in common at all. 
He calls in Dr Green to try and help profile the killer(even though she has not experience or expertise in this field!)

This one for me is just ok. Interesting enough premise but a few bits to annoy to stop it scoring higher. Firstly Greens decision to act as a consultant on one of her clients cases just seemed a bit of an unrealistic scenario. She also makes some pretty stupid decisions, especially towards the end of the book which seemed totally illogical. Their whole sexual chemistry thing also felt quite clumsy and a excuse to throw them together in a professional capacity which just didn’t seem realistic at all. 

Also this is titled as a Lockhart and Green book but to be honest it isn’t. It’s a Lockhart book. Green is very much a secondary character, one of numerous in the book. Lockharts female colleague Smith features at least as much if not more than Green. 

While the premise for the story is sound, the book does feel overlong for what it is. It dragged a bit for me and felt a lot longer than it needed to be. Too much padding and pontificating for me to hold a real interest or build any real tension. 

It’s not a bad book per say but too many irritants for me to enjoy to any great degree. 

Many thanks to Netgalley, Bookouture and Chris Merritt for an ARC in exchange for an honest review.
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Wow! AH! ( Speechless ) And This book is complete of the fucking scale and truly marvellous. 

Detective Dan Lockhart acting as SEO is called to a crime scene of a young woman which he thinks is linked and eerily similar to another previous murder he worked on. 

This has an incredibly unique MO where the killer uses a metal ball to choke his victims and damages one finger with a ring. 

Detective Dan Lockhart calls in Doctor Lexi Green, A Psychologist. To help them form a profile and provide more insight and psychological help with this serial killer. 


Detective Dan Lockhart is an arduous well-rounded, likeable character. I took to Dan straight away. Chris has evidently taken a lot of time centralizing on crafting the characters and their development which shows brilliantly. 

He has previously worked in the armed forces and that of his wife going missing over 10 + years ago has caused some trauma etc which is exceptionally well laid out throughout. Brings forward awareness. 

I am excited for book two to carry on seeing his character development some more. 

Psychologist Doctor Lexi Green 

She is a feisty, rebellious and a very independent character. There is nothing unlikable about Lexi. She is Clever, Fascinating, Determined and stubborn as a mule. 

She is currently giving Lockhart therapy due to his trauma. She is then brought in to help Lockhart and his team to find a Serial Killer. 

I love Dan and Lexi's relationship even if it complicated and on/off at times. I can't wait to continue on the train of both their individual developments and together. 


It was the right consistency of pace. At 400+ pages it is a longer book which took me a few days to read. It is a very detailed and keeps you turning the pages rapidly although it is a creepy, gruesome, fearful, nightmarish and ominous novel. 


I positively enjoyed Chris Merritt's writing style. It is detailed but also not bogged down with too many details. It is a genuinely exceptional piece of well-crafted writing. 


An eye-catching cover which appeals to the eyes straight away. Beautiful colours. 

Overall Thoughts 

It was a sensational read with many potential suspects. And I honestly had no idea who the killer was until it was revealed. 

It takes a fabulous clever author that can take you down deep underground while guessing and guessing until the final sucker-punch explosive finale. 

I Highly recommended. It is another marvellous thrilling book of the year so far here at RTTP.
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EXCERPT: If she'd known it was to be her last night alive, he wondered, how would she have spent it? Gossiping in an over-priced bar with her friends and dancing until the early hours? Or hooking up with one of those square-jawed randoms she seemed to collect on Tinder? Perhaps she'd get sentimental, gathering her relatives privately for a solemn, tearful goodbye. Knowing her though, his guess was hosting an obscenely expensive, self-aggrandising charity bash with champagne and fireworks. She certainly wouldn't have chosen to sit alone like this, tapping away her final hours at a computer.

ABOUT THIS BOOK: Natasha Mayston wasn’t expecting anyone to knock on her door so late at night. And she has no idea that the face staring back at her is the last one she’ll ever see…

As Detective Dan Lockhart is called to a wealthy London street to investigate Natasha’s death, he’s startled by the similarity to a previous case. Noticing the cable-tie restraints and the tiny scratches on Natasha’s wedding finger, Dan already knows what he will find if he looks in her mouth – the metal ball which choked her to death. He knows Natasha isn’t the killer’s first victim and is certain that he will strike again.

Months earlier, Kim Hardy was found in the same position in a run-down hotel across the city – an identical silver ball in her throat. But Kim’s murderer was caught and sent to prison – did they arrest the wrong man? And what connects the two victims? Fearing that he’s dealing with a psychopathic serial killer, Dan calls in psychologist Dr Lexi Green to help him to get into the perpetrator’s mind. Tough and smart, Lexi will stop at nothing to hunt down the man responsible for the deaths.

Then, another body is discovered, just as Lexi finds a clue online leading to the killer. Dan’s team aren’t convinced, but in pushing Lexi away from the investigation, they force her to dig further into the case on her own. Convinced that she’s on to something, she puts herself in unthinkable danger… but can Dan piece together the clues and identify the killer before it’s too late?

MY THOUGHTS: I started this book with great excitement. I love this author's Zac Boateng series, and I was looking forward to more of the same. WRONG. Knock Knock is very different. Where I found the Zac Boateng series to be fast paced, suspenseful and thrilling, Knock Knock seems to be drawn out and, to be quite honest, I found myself skimming passages where the author seemed to be pontificating/procrastinating. Don't get me wrong - this is not a bad read, and I will give this series a second chance, but it needs to be tightened up, to be not quite so bogged down in repetitive psychological analysis.

I liked the characters: Dan, Detective Lockhart whose wife has disappeared without trace; Maxine Smith, a strong character inclined to follow her instincts; Lexi Green, psychologist, who also has trauma in her past. Even the lesser characters, the supporting cast, are an interesting bunch. The chapters written from the POV of the murderer were mostly interesting, but a little repetitive.

The basic plot is sound, and there are a few interesting twists and misdirections. I did have fun trying to guess the killer - I didn't even come close.

I hope this does develop into a good series. I know Merritt has the talent.

Love the cover. *:)


#KnockKnock #Netgalley

THE AUTHOR: Hello! I'm a British author whose crime thrillers combine psychology, suspense, and characters you care about.

All my novels are set in London, where I live. My first trilogy starred Zac Boateng and Kat Jones, two detectives motivated by family, who tackle organised crime and police corruption. LAST WITNESS, the second Boateng and Jones book, reached #13 in the UK Kindle chart in 2019.

My second series features detective Dan Lockhart - an ex-soldier with a missing wife - and psychologist Dr Lexi Green, an American living in London. These novels are darker, more psychological serial-killer cases, with romantic relationships as a central theme.

I began writing fiction in 2014, after previous careers as a diplomat, based in Iraq and Jerusalem, and later as a psychologist working with victims and perpetrators of crime. I specialised in treating Post-Traumatic Stress Disorder (PTSD), which sparked my interest in telling stories about how people cope when faced with extreme adversity.

Now, I spend most of my time writing novels and drinking coffee while 'thinking' about writing novels. When I'm not writing, I love climbing and playing basketball.

DISCLOSURE: Thank you to Bookouture via NetGalley for providing a digital ARC of Knock Knock by Chris Merritt for review. All opinions expressed in this review are entirely my own personal opinions.

For an explanation of my rating system, please refer to my profile page or the about page on

This review and others are also published on Twitter, Amazon and my webpage
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This is the first book in a new series featuring DI Dan Lockhart of the Putney MIT and Dr. Alexis (Lexi) Green, a psychologist with the NHS. Although she's been seeing Lockhart as a patient, a series of linked murders forces him to use her expertise to help develop a profile of the killer. The murders are brutal and all the victims are women. There's no shortage of suspects but the case and investigation are going nowhere despite the team working full out. NO SPOILERS.

A very well-written crime thriller and police procedural with an unusual theme to motivate the killer. It held my interest and I definitely want to learn more about the two main characters as well as those who are part of Lockhart's MIT 8. There's a bit too much hinting of more than professional interest between Dan and Lexi and, honestly, I don't want to see a romance there. Hopefully Dan will stay focused on finding out what happened to his missing wife...

Thank you to NetGalley and Bookouture for this e-book ARC to read, review and recommend. I've read the 3 books in the Zac Boateng series and look forward to the second in this one.
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Thank you to #NetGalley and #ChrisMerritt and the publisher for the opportunity to read "Knock Knock", the first book in a new series, featuring Detective Dan Lockhart and Psychologist Lexi Green in return for a fair review.

Four women, murdered in the same diabolical way: one was a prostitute, one a philanthropist, one an 'influencer' and the other a crusaders for the rights of battered and abused women. The one thing they have in common is the method of murder. Although another police precinct believe they have the person responsible for the first murder (the prostitute, which took place months prior to the case where we are introduced to Detective Dan Lockhart and Dr. Lexi Green) - Dan is not so sure; the similarities are just too close. But his superiors will not allow him to re-open the other case.

As more bodies are added to the list, we are plunged into a world that has been much in the news these last few years - the world of the incel: men who are involuntarily celibate because of their perceived unattractiveness, and their subesquent hatred of women.

This plot kept me guessing throughout, and every time I thought that I knew who the killer was.... I was proven wrong (as were Lockhart and Green). When the climax finally arrived - at great personal loss to Dr. Green - I was as surprised as they were.

A great read, and I cannot wait for the next book in the series.

Highly recommended.
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I really enjoyed this book!  A great story line that kept me hooked and excellent main characters.  I would highly recommend this book.
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This was an interesting police procedural, covering a string of serial killings in London.  It primarily centers on the DI, Dan, but you also get to know the other members of his team, as well as psychologist Lexi Green, who is pulled in to assist.  There is also a side story related to Dan trying to find his wife, Jess, who disappeared 10 years ago while he was deployed with the military in Afghanistan.

The story itself was interesting and moved at a fast clip- I liked the glimpses into the killer's mind, as well as the intent to get us to know the victims a bit before they met their demise.  I thought the detective work was well done, for the most part, and Dan's relationship with his boss seemed real.  I struggled a little with Lexi, who seemed a bit immature and took unnecessary risks, though I did appreciate her determination.

I didn't guess who the killer was, but that was because it came entirely out of left field.  I thought the author did a great job in leading the reader to follow a few different threads in guessing the villain, but then I was underwhelmed when I found out, as I didn't feel I had gotten enough information to care whether that person did it or not, or enough to even lead me in that direction.  

Overall, this was a good read and I'd recommend it to fans of the genre.  I would have given an additional star if there had been more lead-up to the unveiling of the killer.  I do look forward to seeing what happens in the next book in this series.
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Firstly, the book is over 400 pages which makes it so long but since is the first book in the new series, I think it deserves it. The author has concentrated more on character development and makes us care for each of them.

The book is dark and gripping with so many twists and turns which are unpredictable. Chris Merritt has written in such a manner that I just couldn't close the book and go to sleep. It haunted me even in my dreams honestly.

Overall, it was a great read and I think the series seems so much interesting. Highly recommended.

Thanks to NetGalley, the publisher and the author for providing me a copy of this amazing book for review. I totally enjoyed it.
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i was intrigued about this book when i read the cover and description. i really liked the characters of lockhart and green and hope to read more about them in the next books to come. 
i felt like the characters were very well rounded and thoughtful. i felt like i was in the killers mind a lot and that was creepy but interesting in the same time. 
i felt like this was a great psychological thriller that kept you thinking until the very end about who did it. so many different possibilities for the suspect. 
i would recommend this to any of my book friends that love a good thriller. 
i was given this book from netgalley and publisher for an honest opinion and review.
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It's night-time and Natasha Mayston isn't expecting visitors. Certainly not the man staring at her from across the street, through her porthole window.

As Detective Dan Lockhart is called to a wealthy street to investigate Natasha’s death, he’s startled by the similarity to a previous case. DI Dan Lockhart is an ex-soldier with a missing wife and is currently working as part of the Major Investigation Team (MIT) in Putney, London. Dan believes Natasha is the victim of a brutal serial killer who bumped off sex worker Kim Hardy in a hotel a few months ago, although another man was charged with her killing and is in prison. Dan calls upon psychologist Dr Lexi Green, an American living in London, to assist, alarmed that he’s dealing with a psychopathic serial killer. Just as Lexi thinks she's got a lead on the killer, yet another body is discovered. But Dan’s team aren’t convinced, and in pushing Lexi away from the investigation, she is forced to probe further into the case alone, putting herself in unthinkable danger… but will Dan be able to identify the killer before time runs out for her?

Knock Knock, the first instalment in Chris Merritt’s exciting new series, is a tense, exciting and superbly crafted police procedural. At 400+ pages, the novel is slightly longer than my usual reads, but Chris Merritt uses the extra words to introduce and develop his characters really well. I really like the delightfully depraved modus operandi of the serial killer and it made for compelling and refreshing reading. The use of a psychologist to create a probable profile of the killer is captivating and there are some shocking twists in this dark tale. With a good number of possible suspects, the author manages to keep me guessing right up to the riveting conclusion. A remarkably good story that I can confidently recommend!

I received a complimentary copy of this novel from Bookouture via NetGalley at my request, and this review is my own unbiased opinion.
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For the most part I enjoyed this first book of a new series. The mystery is interesting and the pacing keeps you engaged. The characters are just beginning to develop and it will be interesting to see them grow. I really liked Lexi. I found her to be complicated as well as determined. I had mixed feelings about Lockhart. He draws Lexi into the case because he respects her opinions and trusts her. He then proceeds to treat her terribly and ignore everything she has to offer. His team has some interesting members and I really dislike Smith. It will be interesting to see how things go in the next book.
The case itself is portrayed in a manner that shows the author did their research. The way the team approaches things keeps you interested without reading like a textbook, which can be a problem with police procedurals. I felt invested in the outcome. I particularly enjoyed the parts from the killers point of view. It added a lot to the suspense. I guessed the killer completely wrong. The author does an excellent job of leading you through the mystery without spoon feeding it to you. I like the writing style and definitely will read more by this author.
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I enjoyed this book, I liked the relationship between lockhart and green and would like to see where it goes. Also would like to know what happened to lockhart wife so I will be keeping a lookout for the next installment.
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I received this copy of this book from netgalley.
I really liked it! Kept me interested. good plots and liked the character's. will be looking forward to reading book 2 when it comes out.
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I loved the series featuring Detective Zac Boateng, which Chris released over the last year or two.  When I heard that he was due to release the first book in a new series, I just knew that I had to get a copy of the book as soon as I could.  The first book in the new series is called 'Knock Knock' and it features a new Detective, Dan Lockhart, who works together with a psychologist, Dr. Lexi Green, to investigate a case of a potential serial killer.
I took to Detective Dan Lockhart from the start.  He is something of an interesting and at the same time complex character.  He did serve in the armed forces but he experienced significant trauma, which still affects him mentally to this day.  Lockhart joined the police force and at the time he was married.  However one day his wife upped and left without any warning and Lockhart doesn't know if she left voluntarily or was taken.  As yet she hasn't been found but Lockhart hasn't given up hope and he certainly hasn't stopped looking for her.  Lockhart sees a psychologist on a private basis, which is where Dr. Lexi Green comes in.  She is his psychologist and he consults her on a case.  They make a strong team and I loved the way in which they seemed so comfortable with each other and the way in which they worked so well together.  I look forward to reading more about their new working relationship in the future.
It didn't take me long at all to get into this story.  In fact by the time I got to the end of the first couple of pages, I just knew that I was going to enjoy this new series as much as I enjoy the Boateng series and that I would find it increasingly difficult to put the book down for any length of time.  That is exactly what happened.  The book wasn't exactly glued to my hand but it might as well have been because it travelled everywhere with me.  I feared that if I put the book to one side I might miss something crucial to the investigation and I had to keep reading to see if Lockhart and Green survived to the end of the story.  I binge read the book over the space of a couple of days.  I would make the mistake of picking up the book only intending to read a couple of chapters but I would still be sat there reading over half a dozen chapters later.  'Knock Knock' was one of those gripping books that had me on the edge of my seat throughout the story.
'Knock Knock' is extremely well written but then I think that to be true of all of Chris' books.  I love the way in which he starts the story with a bang, which immediately grabs your attention and he then takes you on one hell of a scary and at times unpredictable rollercoaster ride.  For me, the story hits the ground running and maintains the pace throughout.  Chris writes so convincingly and so realistically that I genuinely felt as though I was part of the story myself and helping Lockhart and Green with their investigation.
In short, I thoroughly enjoyed reading 'Knock Knock' and I would definitely recommend it to other readers.  It is a great start to what I am sure will be a fantastic series.  I will definitely be reading more of Chris' work in the future.  The score on the Ginger Book Geek board is a very well deserved 5* out of 5*.
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What a great way to kick off a new series! I loved the introduction to the two main characters, and their interactions were natural. I thought the teamwork of the investigation was realistic and well-researched. What made this book stand out was deep dive into the killer’s world. It was fascinating and creepy, which added depth to the story. If this is any indication of what’s to come, I can’t wait to read more of this series. For a full review, please visit my blog at Fireflies and Free Kicks. Huge thank you to NetGalley and Bookouture for a digital ARC of the book.
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A good and twisty psychological thriller that keeps you guessing till the end! Very clever writing with many suspects who are all very believable killers! 
I can see this turn into a really good series and can't wait to read more. 

What is the lesson we can learn out of this book?

Thank you to Netgalley and Bookouture for the ACR in exchange for my honest opinion.
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I love police procedural series and especially those with serial killers/psychological element, makes them all the more tasty and enthralling. 

This is the first book in the Lockhart & Green series and a great introduction to what is going to be a very promising series.

Det Dan Lockhart is called in to the scene of a murder of a woman killed in her home, however, alarm bells start ringing in Dan’s head, dejavu, he has seen a crime scene like this before, the woman is tied to a chair, bruising/marks on her ring finger and a metal ball lodged in her throat, however the difference in this murder scenario is that this is a very wealthy rising star that has been murdered and the other murder was that of a prostitute, how do these cases relate or do they, is he seeing similarities that are just not there?

We see a lot of insight into Lockhart’s troubled past, his wife has been missing for 10 years and also suffering from PTSD from his service in the army, he attends Dr Lexi Green to help him work things through, however, Lockhart believing they have a serial killer on their hands, enlists the help of Dr Green to give an insight into the mind of the serial killer so does this affect their professional client/doctor relationship? Although they seem to figure out the reason why, now they need to catch the perpetrator before more bodies turn up! I thought I had figured out the killer, however, obviously I was wrong because this will be revealed only when good and ready.

I thoroughly enjoyed the book, it had everything I look for, serial killer for starters, a good kick off to the book with an immediate murder, mystery, suspense, red herrings…. What more could you ask for!!! 

Really looking forward to where the series brings us next and discovering more about the personalities, traits of the characters as they develop more throughout.
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DI Dan Lockhart's wife disappeared ten years whilst he was deployed overseas with the army and hasn't been heard from since. Lockhart is in therapy with Lexi Green to work through his issues, but they both become involved in a case when women are murdered by a serial killer with a particularly nasty method of killing. 

The book is told from several points of view including Lockhart, Green, and the killer. The first book in the Lockhart & Green series is a fast-paced read, with plenty of twists and turns. I narrowed it down to three suspects but turned out to be completely wrong. The author used the issue of the proliferation of misogynistic websites as a background for the case so be warned: there are several scenes of violence against women, and misogynistic speech. There are a couple of loose ends which I expect will be followed up in the next books, and I wouldn't mind reading the next one. 

Thanks to NetGalley and publishers, Bookouture, for the opportunity to read an ARC.
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I am a huge fan of the author’s other series so when I saw that this book, Knock Knock was being released and it was the first in a new series I couldn’t wait to get my hands on a copy – and after seeing that stunning cover I was even more excited to get started on it!

I thought that the story was well developed and I loved meeting the new team of featuring Detective Dan Lockhart and psychologist Dr Lexi Green, who I think work really well together.  I am really keen to find out more about Dan’s personal life and back story as he seems an intriguing character!

I found that the story was well written and it was set at a great pace for the story.  I thought that it was an addictive story and I flew through the paged as I needed to see how it would all end and how it would be wrapped up – and I was certainly not disappointed!!

It is 5 stars from me for this one, I thought it was an excellent story and a brilliant start to a new series and can’t wait to read the next book in the series now – very highly recommended!!
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This is the first book I've read by this author but it certainly won't be the last.

It was dark, twisty and kept me guessing til the end. I found myself reading faster and faster as I had to know who it was!

Dan and Lexi are great characters and I look forward to reading more about them.
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