A young woman is murdered in a park in Minneapolis. When detectives Gino and Magozzi discover a playing card near the body, they recognize the work of a serial killer whohas already struck the city once before. But it's worse than they imagined. The card is the four of spades, the last victim was the ace: it seems they're already two murders behind. Once again working with Grace MacBride and her team of analysts, they discover a web of evidence stretching back into the past. And there is little time to untangle it: this killer has a taste for blood, and he's intent on playing out the deck...