While on a helicopter ride to Santa Barbara, Mannix witnesses a man strangling a woman on a penthouse terrace. However, when he investigates, the occupants of the penthouse say that there has been no foul play.

Mannix is brought to a small town in New Mexico under false pretenses, where he is then served a subpoena and must testify as an expert witness for the prosecution in a murder trial; he stays on the trial as the aid to the defense.

The owner of a jewelry shop is murdered. When Mannix arrives at the crime scene, he runs into an old friend from his days in the Korean War who asks him to visit a small mountain town where he can gain information on the situation.