When DI Tess Fox arrives at her first murder scene there are already two big problems. First, the victim was thrown from the balcony of an apartment locked from the inside. Second, Tess knows the victim, and a clue left at the scene means the killer knows that too.

Only one person knows about Tess's link to the victim and has the skills and criminal background to mastermind a locked-room murder. But Tess's half-sister Sarah is a con-artist, not a killer. And Tess is going to need her expertise if she's ever going to crack the case.

Soon two more bodies turn up in equally mysterious circumstances and also known to the sisters. Tess now has three locked room mysteries to solve and even more reason to be suspicious of Sarah. Can she trust someone who breaks the law for a living, even if she is family?