The unthinkable has happened at Londons Peculiar Crimes Unit. In the bitter depths of winter a key member of staff has been found murdered & everyone who works there is suddenly a suspect. But Arthur Bryant & John May the eccentric elderly detectives who run Londons strangest crime division arent on hand to solve the crime. Theyve ventured into the heart of the English countryside only to become stranded on a desolate snowbound section of road. As the blizzard worsens Bryant & May attempt to solve the crime long distance using only their mobile phones. Unfortunately their situation is about to get very much worse. Unknown to the stranded detectives an obsessed killer has travelled from the Riviera to Dartmoor & is stalking the stranded vehicles searching for one particular victim coming closer with each passing minute... As if it didnt have enough trouble the Peculiar Crimes unit is about to receive a demanding royal visitor & the Home Office is preparing to shut the PCU down when the visit inevitably goes wrong... Two murderers two incapacitated detectives just six hours to solve two crimes & save the unit. Armed only with their wits woolly coats & a stack of dubious veal & ham pies Bryant & May are bracing themselves for the strangest day theyve ever spent trapped inside the white corridor...