Season synopsis
Contains spoilers for this season and earlier seasons.
Abigail Mitchell believes her niece’s husband killed the young woman, so she locks him inside her soundproof safe and flies away. Edmund alters a manuscript title page to accuse Abigail and hides it in the safe’s light socket. Columbo finds it and arrests her despite her appeal for sympathy. In another case, critic Paul Gerard poisons a restaurateur with blowfish toxin after the victim threatens to expose his extortion scheme. Columbo tests Gerard’s account of the wine service and turns the suspect’s own bottle-opening method into a demonstration that exposes how the poison was delivered.
Kay Freestone tries to fit her boss’s murder between film reels, but Columbo’s planted imitation gun becomes revealing when she retrieves it. Dr Eric Mason’s Dobermans kill on a phone-triggered word; Columbo catches the command on a recording, then has the dogs retrained so Mason’s final order becomes evidence rather than another victim. In the last case, poet Joe Devlin kills his arms-deal middleman; a diamond-ring mark on a whiskey bottle and a tug carrying guns expose both the murder and the smuggling plan. Mason’s victim had been having an affair with his late wife. Devlin’s charitable fundraising conceals his work supplying weapons to the IRA.