Whilst driving his Rover P5B, uptight City worker Harold Pelham appears to become possessed and he has a serious accident at high speed. On the operating table, he briefly suffers clinical death, after which there appear to be two heartbeats on the monitor. When he awakes, Pelham finds his life has been turned upside-down: in his job as a director of a marine technology company he learns that he now supports a merger that he once opposed, and that he apparently is having an affair. Friends, colleagues and acquaintances claim to have seen him in places where he has never been, also a silver sports car a Lamborghini Islero starts to follow him around. Does Pelham have a doppelgänger - or is he actually going insane?