Embarking on their most daring time-travel experiment to date, Depression-era cop Steven Blackwell and his 21st-century partner-in-crime Olivia Watson travel to the Adirondack Mountains for a Christmas party at one of the legendary Great Camps. Their host, a wealthy New York publisher, has planned a weekend filled with holiday activities, but, as the last guest arrives, temperatures plummet, and a blizzard hits. Before long, the area is buried in snow, the roads are impassable, and the publisher is poisoned.

Unwilling to wait until the local police arrive, the victim's widow convinces Steven to launch an unofficial investigation. Soon, a family member goes missing, and Steven and Olivia discover a second victim. Trapped with a killer, Steven and Olivia race against the clock before the murderer strikes again.