Four strangers are missing. Left at their last-known locations are birthday cards that read: YOUR GIFT IS THE GAME. DARE TO PLAY? The police aren't worried - it's just a game. But the families are frantic, and psychologist and private detective Dr Augusta Bloom is persuaded to investigate. As she delves into the lives of the missing people, she finds something that binds them all. And that something makes them very dangerous indeed. As more disappearances are reported and new birthday cards uncovered, Dr Bloom races to unravel the mystery and find the puppeteer. But is she playing into their hands?