It's the classic locked-room mystery—a member of the Peculiar Crimes Unit killed inside a sealed morgue populated only by the dead and to which only four PCU members had a key. To make matters worse, the Unit has been shut down for a forced “vacation,” and Bryant and May are stuck in a van in the Dartmoor countryside during a freak snowstorm. Now they'll have to crack the case by cell phone while trying to stop a second murder without freezing to death. For among the line of trapped vehicles, a killer is on the prowl, a beautiful woman is on the run, and an innocent child is caught in the middle….