Thirty-one-year-old Felicity Benson is an insecure television producer who is surprised when her boss, film-maker legend Laurie Nattrass, hands her his pet project, a documentary detailing the stories of women who were falsely accused of murdering their children, and announces his retirement. As Felicity begins interviewing these mothers, she receives a strange item in the mail - a card containing 16 numbers, arranged in a tidy grid. Soon she discovers the police are investigating crimes related to two women featured in the film who also received a card from the mysterious sender. One, assaulted on the street, the other, murdered in her own home.

This latest novel in the Spilling CID series by Sophie Hannah is my favorite so far. Hannah constructs a well-honed mystery with distinctive characters and sophisticated writing. DC Simon Waterhouse is once again pitted against his boss, "The Snowman", who was the arresting officer in the case involving the murdered mother, and we get to watch their relationship deteriorate even further. This plot was an extremely straight forward murder mystery, avoiding some of the confusing twists present in her previous novels. However, in true form, Hannah keeps the reader guessing until the shocking and unforgettable ending.