As he is about to be operated on in a hospital amphitheater in Chile, a patient calling himself Fred Dobbs recalls his past life as Peter Ingersoll, a struggling California insurance salesman with a wife, Nancy, and two small children: One day, Peter's best friend, Dr. Scott Carter, informs him that he is suffering from a serious heart malfunction and has only a few months to live. When Nancy hears the sad news, she persuades Peter to go on a worldwide fishing trip, using nothing but credit cards for payment. But Peter's last fling is cut short in Portugal when Carter arrives with word that the electrocardiograph was malfunctioning and Peter's heart is healthy. Faced with $100,000 in credit card debts, Peter agrees to Carter's suggestion that he fake his death, allow Nancy to collect his insurance money, and stay in hiding until the 7-year statute of limitations has expired. Using the dead body of a Negro for a corpse, Carter signs Peter's death certificate, and Peter assumes the identity of Fred Dobbs. But Peter discovers by accident that Nancy and Carter cooked up the scheme to get rid of him, and he works out a diabolical revenge. Switching the corpses of the Negro and a dead Southern colonel, Peter drops one of Carter's calling cards into the colonel's coffin and then takes off for Chile. After the colonel's widow finds the wrong corpse and Carter's calling card in her husband's casket, law officers appear at Peter's funeral and arrest Nancy and Carter as they are about to bury the colonel. Back in the operating room, the patient explains that he was living a perfectly happy life on a fishing boat off the coast of Chile until his chest was pierced by a swordfish.