Lieutenant Jonathan Stride knows his partner, Maggie Bei, is in trouble when she reports a deadly crime on a bitter winter night. She's obviously hiding a terrible secret, and her silence only feeds suspicion. But Maggie isn't the only one keeping secrets in Duluth. A seductive young woman has disappeared, leaving behind a stash of lurid fantasies and a cryptic message: "I know who it is."Following a twisted trail, Stride uncovers a sordid web of violence and voyeurism that someone is willing to kill to keep hidden. His lover, Serena Dial, a homicide cop turned private investigator, is chasing a blackmailer who knows all the city's dirty secrets—even Maggie's. But as Stride and Serena hunt for a killer, a predator is hunting them—with a terrifying plan for revenge.