Season synopsis
Contains spoilers for this season and earlier seasons.
Lieutenant Columbo investigates murders concealed behind professional success, money and carefully constructed alibis. Mystery writer Ken Franklin kills the partner whose talent supports their shared career, then murders a witness who tries to blackmail him. A surviving story note exposes the supposedly perfect plan. Private investigator Brimmer kills a client's wife after she rejects his blackmail attempt, then joins the investigation himself. Columbo catches him searching his car for a contact lens that the detective has planted as bait.
Other investigations turn on the gap between what killers claim and what their actions reveal. A general manipulates a witness after shooting his accomplice, but his treasured revolver links him to the crime. An art critic murders his uncle and frames his aunt, only for Columbo's fingerprints on stolen paintings to undermine the frame-up. Beth Chadwick stages her brother's shooting as an accident; a witness's recollection of the gunshots occurring before the alarm destroys her account. In “Short Fuse,” a chemist uses exploding cigars to kill his uncle, then betrays himself when Columbo produces a harmless replacement box.
The season closes with architect Elliot Markham trying to keep a development project alive by making its wealthy opponent disappear. Columbo suspects murder, partly because the missing man's car radio is tuned to music he disliked, but still needs the body. Markham encourages him to search a building foundation, knowing it is empty. After the excavation finds nothing, the architect returns with the corpse, expecting that nobody will search the same place twice. Columbo has anticipated that move and waits with the police, turning Markham's concealment scheme into the means of his arrest.