Therese Raquin is married to her sickly cousin and begins an affair with Laurent, a friend of her husband. They drown the husband, while out on a boat trip. This enables them to marry, but their guilt comes between them. They also have to look after Therese's elderly mother-in-law, who has suffered a stroke. She discovers their crime, and attempts unsuccessfully to expose them. Eventually, they find life together intolerable and both commit suicide.