American professor and novelist Tom Ricks has gone to Paris to heal his marriage and see his young daughter. But his wife rejects him and soon after, he is robbed, and he ends up living in a seedy hotel and working as a night watchman to pay his rent. Tom's life takes a turn when he meets a sophisticated woman named Margit at a literary event and they have an affair. Margit encourages Tom to write again after a long dry spell, but as he turns his attention to working on a new novel, he is unsettled by a series of murders taking place around him.