The unthinkable has happened at London's Peculiar Crimes Unit. In the bitter depths of winter, a member of the team has been murdered, and everyone who works there is a suspect. With the exception of Arthur Bryant and John May that is, for the eccentric detectives who run London's strangest crime division are stranded on a desolate snowbound road somewhere in the West Country on their way to a spiritualists' convention. As the snows worsen, Bryant & May attempt to solve the crime long distance. And their situation is about to get much. much worse. Unknown to the elderly detectives, an obsessed killer has travelled from the Riviera to Dartmoor, and is stalking the stranded vehicles, searching for one particular victim and edging ever closer with each passing minute...

Two murderers, two incapacitated detectives, just six hours to solve two crimes and save the unit. Armed only with their wits, woolly coats, a mobile phone with a fading battery and some dubious veal and ham pies, Bryant & May are bracing themselves for a strange and very dangerous day...