During the last days of World War II, the British Merchant Navy ship Mount Kyle is torpedoed by a German U-Boat off the coast of Venezuela. The crew are subsequently massacred as they abandon ship, leaving one survivor, an Irish engineer named Murphy (Peter O’Toole). After being rescued by Louis Brezon (Philippe Noiret), a caretaker for an oil company which has a pipeline in the area, he is taken to a local missionary medical facility run by Dr. Hayden (Siân Phillips). Upon recovering, Murphy becomes determined to find the U-Boat that sank his ship and seeks revenge. However, as the war is clearly drawing to a close Dr. Hayden is reluctant to help him and tries to dissuade him from his plan as it may endanger the local community. In the meantime, Murphy finds a damaged Grumman J2F Duck floatplane from his ship and salvages it. With the assistance of Louis, he makes some improvised munitions and draws his plans against the Germans.