Harry Ricks is a man who has lost everything. A romantic mistake at the small American college where he used to teach has cost him his job, his marriage and his relationship with his only child. And when the ensuing scandal threatens to completely destroy him, he votes with his feet and flees... to Paris.
Arriving in the French capital in the bleak midwinter, a series of accidental encounters lands him in a grubby room in an even grubbier quarter, and a job as a nightwatchman for a sinister operation.
Just when Harry begins to think that he has hit bottom, romance enters his life. Her name is Margit - an elegant, cultivated Hungarian emigre, long resident in Paris - widowed and, like Harry, alone.
But though Harry is soon smitten with her, Margit keeps her distance. She will only see him at her apartment in the fifth arrondissement for a few hours twice a week, and remains guarded about her work, her past, her life.
However, Harry's frustrations with her reticence are soon overshadowed by a ever-growing preoccupation that a dark force is at work in his life - as punishment begins to get meted out to anyone who has recently done him wrong. Before he knows it, he finds himself of increasing interest to the police and waking up in a nightmare from which there is no easy escape.