In order to authenticate some historical papers in a cathedral town, Oxbridge academic Anderson stays at a local hotel in room 12, initially disregarding the lack of a number 13 as provincial superstition. During the night, noise conspires to keep him awake and the historian is astonished to come face to face with door number 13. Continuing his work, a history of a reformation era witchcraft scandal emerges. The nocturnal disturbances escalate, leading Anderson with no choice but to open the door to room number 13....