Three fishermen--Marty, Kick, and Joe--find an abandoned yacht with a corpse aboard. They report the discovery to the Coast Guard and are offered the vessel as a charter boat if they will be on the lookout for the yacht's owners, suspected dope smugglers. Marty's girl friend, June, brings the first charter customer, Dick Kane, who soon involves them all in the smuggling of $500,000 in heroin which he knows is on board. After picking up Dick's boss, Sidney Manet, in La Paz, Mexico, Marty is ordered to go to Catalina. Once there the thugs take the heroin and leave in a speedboat. As they disembark, Dick gives June a note telling her that Manet has placed a time bomb in the engine room. Marty throws the bomb overboard and Manet sees the explosion. Realizing his plot has failed, Manet heads the speedboat back towards the yacht. The two vessels collide, and the speedboat is sheared in half.