Captain "Gorilla" Larson earns his nickname by being a brute and a womanizer and regularly beats his crew members for minor infractions. While at sea, Gorilla picks up Philip Wells in a rowboat. Philip claims that after his yacht caught on fire, he was unable to find his wife Helen and friend, Dave Burton. Gorilla is suspicious of his story and drops anchor, and a short time later, Dave and Helen are rescued. Gorilla has Helen installed in his cabin, while without even seeing Dave, has him locked in a guest cabin. Thinking they are alone, Philip tells Helen that he deliberately scuttled the yacht to kill her and Dave because he believes they have been having an affair. Helen denies the affair, but pressured by Philip, admits that she loves Dave. Gorilla overhears the conversation and, disgusted by Philip, orders him to sleep and work with the crew. Gorilla arranges for a dinner alone with Helen and begins to force himself on her, but Benny, the cabin boy, has conveyed a note from Helen to Dave telling him she fears Gorilla. Dave knocks out his guard and comes to Helen's rescue, at which point Gorilla recognizes Dave as a long-ago friend and sailor who once saved his life. Gorilla's demeanor immediately changes and he sends for Philip and intimidates him into offering Helen a divorce. Gorilla announces his intention to kill Philip and write in the logbook that he was a menace to the ship. Helen and Dave plead with him not to kill Philip, and Gorilla gives in, in spite of his better judgment. Now filled with a kindness and generosity previously unknown to him, Gorilla becomes Helen's and Dave's loyal friend and desists from beating his crew. In the meantime, Philip incites the crew to mutiny by telling them that Helen gave Gorilla valuable jewels for saving them, and convincing them that it was they who saved her. The crew knocks out the first mate, and Philip takes Gorilla, Helen and Dave hostage, intending to allow a vengeful sailor to have his way with Helen. Dave hits the sailor and Gorilla struggles with Philip. The lamp is knocked over, and in the darkness, two gunshots are heard. Gorilla, Dave and Helen emerge above deck, and Gorilla takes on the crew, beating them into submission, while the recovered first mate puts Helen and Dave into a lifeboat on Gorilla's orders. After Gorilla kills one sailor, the crew takes his orders again and starts fighting the fire that has risen from the fallen lamp. Knowing that Dave and Helen are in the international shipping lane and will be rescued, he shouts his best regards and sails off.