Ensign O'Toole finds himself weight managing rotund seaman Tubby Mason (Stubby Kaye.) Lieutenant Commander Virgil Stoner wants to discharge him for being too fat and holding Tubby responsible for the food supplies running low.
Ensign O'Toole makes a deal with Stone. That Tubby will lose weight in thirty days.
Only it is no easy task for Tubby to stop eating. When they give him less food. Tubby finds creative ways to obtain food. Ensign O'Toole even gets the boys to fix the weighing machine but Stoner is too smart.
Maybe Ensign O'Toole is finally sunk but Tubby finds a way to keep himself afloat. Transfer to a submarine.
Nicely humorous but also predictable for its time. One of actor Stubby Kaye's final appearance was in a Doctor Who story.