When a freak blizzard descends on Manhattan, Erin O'Reilly plans to take shelter and wait for it to blow over. But Irish mobster Evan O'Malley has other ideas. He's heard there's an undercover cop in his organization and wants Erin to unmask the infiltrator. Phil Stachowski, Erin's handler, is in danger, and he's gone missing.

Erin finds herself plunging into the heart of the storm. She finds one dead cop and another clinging to life. And that's not the worst of it. The evidence points to a traitor in the NYPD, a cold-hearted killer who is willing to do anything to get what he wants-the truth about Erin herself.

As the snow and the bodies pile up, Erin and her K-9 Rolf wade through a blinding, deadly flurry of suspicion and danger in which it may be impossible to tell friend from foe until it's too late. And in the end, the coldest choice will come down to Erin herself: what can she do when protecting her secret means betraying herself?