Living in witness protection, ex-undercover police officer, Tom Killgannon, finds himself summoned back to work by a local task force headed by DS Sheridan. His mission puts him inside Blackmoor prison, where he is tasked to befriend Noel Cunningham, a child killer, to try to ascertain where he has hidden two of his victims’ bodies that have never been found. A prison is a dangerous place at the best of times, but Tom’s life is put at risk when he is identified by Dean Foley, a convicted gangster who was put away thanks to his testimony. Realising that this is not going to end well, he tries to contact DS Sheridan, but is unsuccessful. What is the real reason for him being put inside the prison and will he make it out alive?

The previous book in this series, The Old Religion, received great plaudits and so I was pleased to be able to take part in the blog tour for the follow up, The Sinner. Although there are some references to events that occurred in The Old Religion, knowledge of what has gone before is not essential and this can be read as a standalone.

From the start of the book, I found myself totally invested in the character of Tom Killgannon. Placed in the witness protection scheme and seemingly enjoying his life, there was a definite air of foreboding when he was asked to take part in another undercover operation. Tom should have listened to his instincts as he could not have envisaged what was going to happen during his time in Blackmoor. Martyn Waites paints a very bleak picture of life in prison, corruption being rife, creating an incredibly unsafe environment for the prisoners. It was fascinating to see how quickly Tom became accustomed to incarceration, and it was easy to see why mental health issues among prisoners are so high.

There is so much happening in this plot, both inside and outside of the prison. While Tom is trying to discover Dean Foley’s motives and attempting to get the information required by DS Sheridan, he’s also worrying about the people he cares about the most on the outside. Pearl and Lila are great characters, and I enjoyed seeing these women come to the fore when danger presents itself.

For me, the most fascinating part of the book is the relationship between Tom and Dean. Through flashbacks, we get to find out about the events that put Dean in prison, and we also see why he would certainly bear a grudge against Tom. There is a definite ‘cat and mouse’ element between these two characters and I was on the edge of my seat waiting for the inevitable showdown.

The Sinner has a tight plot and is a great thriller that became even better as the book progressed. Just when I thought everything had concluded, Martin Waites hit me with a superb twist that I hope will be explored in further books. This is a great read and I recommend it highly.

With thanks to Zaffre Books and to Tracy Fenton from Compulsive Readers for organising the blog tour.