Louis (Jean-Paul Belmondo) is the wealthy factory owner living on a French island off the coast of Africa. When he advertises for a mail order bride, he receives a picture and letter from the woman who agrees to join him. The woman who shows up is not the one in the photo, but Julie (Catherine Deneuve) explains she sent the picture of a friend. The two are soon married and Louis takes ill soon thereafter. As his health worsens, Julie leaves after depleting their joint bank account of all the money. After a frantic drive to the bank, Louis hires a private detective to search for her. Locating Julie in a sleazy dance hall, she explains she is an orphan and was forced into the scam by a man she met on board the ship. The man killed the mail order bride and dumped her body overboard, replacing her with Julie to bleed the wealthy Louis dry. The two try to reconcile after Louis shoots and kills the detective. Hiding out in a remote mountain cabin, Julie slowly poisons Louis with rat poison in this disturbing story of greed and murder.