Bruno Anthony is a charming psychopath on board a train to New York, when he meets a tennis pro called Guy Haines. Guy is going through an unhappy time in his marriage, and wants to divorce his wife Miriam. Bruno's problem is with his father, but he wants a more permanent solution. He wants him to die... The plan is relatively simple. They each agree to kill someone the other person wants disposed of. It's the perfect murder! Isn't it?