No Night Is Too Long

No Night Is Too Long is a 2002 BBC dramatization based on the novel of the same name by Barbara Vine a pseudonym of Ruth Rendell.

Surprise ending revealed Meanwhile, Ivo, who was not actually killed and has escaped from the island where Tim left him, confronts Isabel about the affair. Ivo then reveals that, unbeknownst to Tim, Isabel is actually his sister who was asked to keep an eye on Tims behaviour while Ivo was away supervising the cruise, explaining his earlier anger. Soon Tim begins to receive anonymous letters making it clear that someone is aware of his crime. Eventually, Ivo turns up in person at Tims house and discusses the previous events with him. Ironically, on leaving Tims house, Ivo is murdered by a deranged drifter who had mistaken Ivo, cloaked in Tims raincoat, for Tim himself. In contrast to the end of the novel, which suggested Isabel and Tim could rekindle their relationship, the films closing scene shows Tim unable to open his door and let Isabel into his house, overwhelmed by the fear that his destructive influence might reach even to her.

Source: Wikipedia