Brimmer, a short-tempered private detective, is hired by Arthur Kennicut, a prominent Los Angeles publisher, to investigate the publisher's wife's activities under suspicion of an extra-marital affair. Although his investigation discovers an affair with a golf instructor, Brimmer chooses not to tell Kennicut about it and proposes Mrs. Kennicut to act, in return for Brimmer's silence, as a "pipeline" for information involving powerful persons with whom her husband is involved. When Mrs. Kennicut refuses to cooperate and threatens to tell her husband about Brimmer's unsavory proposal, Brimmer becomes enraged and accidentally kills her. He then transports her body across Los Angeles and dumps it in an industrial area, hoping her death will look like a robbery gone awry. Enter Lieutenant Columbo, the cigar-smoking detective in a rumpled raincoat, who does not accept the murder-by-mugging theory surrounding the woman's death. When Kennicut assigns Brimmer to assist Columbo in the murder investigation, Brimmer struggles to deflect Columbo's increasing suspicions that he was involved in Mrs. Kennicut's demise.