One by one, he'll stalk them, then he'll squeeze the trigger, savoring the way each lifeless body crumples to the reddening snow. One down already. And then there were five.... When Detective Regan Pescoli drives to Sheriff Dan Grayson's house to present her resignation, she's prepared for an argument. She's not expecting to find Grayson shot and bleeding out on the frozen ground. The assassination attempt leaves Grayson barely clinging to life and the entire police department of Grizzly Falls, Montana, in shock. Every lawman has enemies, but something about this shooting suggests more than a simple grudge. Now Pescoli feels compelled to stay on the force until the case is solved. She and Detective Selena Alvarez - who is torn between a new relationship and her loyalty to Grayson - work to whittle down the list of suspects. But the deeper they go, the more personal and dangerous the case becomes.

Then a prominent judge's body is found and the killer sends a sinister warning to the press: “Who's Next?” Headstrong and eager for justice, Pescoli has no intention of waiting around to find out. She'll track the scant clues on her own if she has to, but she has no idea where her search will lead.... Two down, four to go... and now Alvarez and Pescoli are at the top of a killer's list. And when hunter meets prey, both must be willing to kill - and ready to die.