Barnaby's cousin, Monroe Jones, a Chicago police sergeant, gets a tip from an informant (Tony Ritter) that the man (Walter Cahill) who murdered his partner six years ago is living in Los Angeles. When Sgt.Jones arrives in L.A. to meet up with Ritter, he is murdered at the airport by the same killer.

Monroe's son, Jedediah Romano (J.R.) Jones, arrives in L.A. to track down his father's killer and to avenge his father's death.
J.R. goes to Barnaby for help in finding Tony Ritter hoping that Ritter can lead him to Monroe's killer.

Barnaby and J.R. follow various leads but it is a phone call that is made while Barnaby is out of the office that leads J.R. to a confrontation alone with his father's killer. Unfortunately for J.R., Cahill is well skilled in karate and easily knocks J.R. out. Just as he is about to kill J.R., Barnaby shows up and shoots Cahill, wounding him so that he can not harm J.R.

After everything is resolved, J.R. decides that he would like to stay in L.A., and asks Barnaby to hire him to work part time while he studies for the California Bar.