"The Unknown" was the final entry in Columbia’s I Love A Mystery series. A woman hires two detectives to keep her alive long enough to claim her inheritance.

Fred J. Johnson scores a hole-in-one but his next drive, using the lucky, initialed golf ball, soars out of bounds and lands near a spot where some counterfeiters are burying a murder victim. Then begins a series of events in which he is hounded and threatened by the killers. The consequences of his not reporting what he saw to the police lead to a climax in which is daughter is held hostage by the crooks.

Pier 23 was one of three hour-long mysteries produced by Lippert Productions for both TV and theatrical release. Each of the three films was evenly divided into two half-hour "episodes," and each starred Hugh Beaumont as San Francisco-based amateur sleuth Dennis O'Brien. In Pier 23, O'Brien first tackles the case of a wrestler who has died of a suspicious heart attack after refusing to lose a match. He then agrees to help a priest talk an escaped criminal into returning to prison.

A San Francisco private eye finds himself under suspicion while investigating a prizefighter's murder.

A San Francisco man is paid to bid on a saxophone and escort a woman to a yacht party.

A nightclub operator, her sister, a beautician and two other women rob a payroll.