Wine producer Adrian Carsini discovers that his younger brother Enrico plans to sell the family vineyards to pay his playboy-life debts, and sets out to murder him. He locks him in a wine vault and turns off the air and conditioning, then drags the body out to the ocean and makes it look like Enrico died during a scuba-diving accident. Columbo is suspicious of the contradictions that show up in the autopsy, and soon realizes that Adrian is the murderer. The final clue is the wine that was spoiled when the vault's air conditioning was turned off. Only Adrian could tell the difference, so Columbo secretly gets him to sample the wine and declare it unfit. Once Adrian realizes his wines were ruined, he is forced to throw them over a cliff, as Columbo looks on. In the end, Columbo takes in a relieved Adrian, confessing that Carsini is one of the few killers he was reluctant to bring in.