The son of a prominent businessman has been murdered in San Felipe. The town suspects Juan Moreno, a migrant worker, but the men at Checkmate think he is being railroaded. They investigate, and in the process, uncover details that are embarrassing to both the defendant and the victim's family.

Victor Ragar, a cellist at a music conservatory that fronts for an Eastern Bloc freedom movement of which he is the leader, is in danger of being assassinated by a compatriot who accuses him of betraying the cause. The would-be assassin, Paul Delorio, also has a personal motive- Victor ran off with Paul's wife while Paul was in prison in the old country. The conservatory's director, also a member of the movement, hires Checkmate to protect Victor.

Jed and Dr. Hyatt go undercover as members of a hobo community to protect a man known as Doc, acknowledged leader of the community. Years ago Doc was disinherited by his wealthy father for behaving irresponsibly with money, but now his dying father wants him back, and others in his family want him dead so they won't have to pay him an allowance. When Doc winds up inheriting the entire estate, he goes to town with it, making Checkmate's job more difficult.