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. As psychologist and private detective Dr Augusta Bloom 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 missing people.

But what if, this time, they are the ones she should fear?