Sarah thinks of herself as a normal single mum. It's what she wants others to think of her. But the truth is, she needs something new, something thrilling. Meanwhile, DI Tom Thorne is investigating a woman's suicide, convinced she was driven to do it by a man who preys on vulnerable women. A man who is about to change Sarah's life. 

Alison Willetts has survived a stroke, deliberately induced by a skilful manipulation of pressure points on the head and neck. She can see, hear and feel, but she is completely unable to move or communicate. In leaving Alison Willetts alive, the police believe the killer's made his first mistake. Then DI Tom Thorne discovers the horrifying truth: it isn't Alison who is the mistake, it's the three women already dead. Thorne must find a killer whose agenda is disturbingly unique, and Alison, the one person who holds the key to the killer's identity, is unable to say anything.... 

Pete Riley is a stay-at-home dad; his partner, Maddie, works in advertising. After Pete drops two-year-old Theo off at nursery one morning, he's politely accosted by a man who looks just like Theo. The man, Miles Lambert, breaks the devastating news that Theo is in fact not Pete's son, but his - the two babies got mixed up at hospital and Miles and his wife, Lucy, now have the Rileys' son at home. They've already carried out DNA testing to prove it.

FBI Agent Nell Flynn is about to work the most personal case of her life. Back home for the first time in a decade, Nell is getting ready to close the family estate after her father's death. But there's one piece of unfinished business. Her father, a homicide detective, was investigating the murders of two young women. Now his partner has asked for Nell's help. Nell soon realises that her father should be the prime suspect, and that his friends on the force are covering for him. 

'And in Edinburgh of all places. I mean, you never think of that sort of thing happening in Edinburgh, do you...?' 'That sort of thing' is the brutal abduction and murder of two young girls. And now a third is missing, presumably gone to the same sad end. Detective Sergeant John Rebus, smoking and drinking too much, his own young daughter spirited away south by his disenchanted wife, is one of many policemen hunting the killer.