A quiet Philadelphia suburb. A woman cycles past a train depot with her young daughter. There she finds a murdered girl posed on a newly painted bench. Beside her is a formal invitation to a tea dance in a week's time.

Seven days later, two more young victims are discovered in an abandoned house, posed on painted swings. At the scene is an identical invitation. This time, though, there is something extra waiting for Detectives Kevin Byrne and Jessica Balzano: a delicate porcelain doll.

It's a message. And a threat. With the killers at large, Detectives Byrne and Balzano have just seven more days to find the link between the murders before another innocent child is snatched from the streets.