This P.I. series ran for 77 episodes between 1957-60. David Janssen stars in the title role.
A man is sitting in a car in the parking lot of a small roadhouse just outside of town. He quietly sits smoking a cigarette while watching the traffic go by. A car pulls in and parks, the occupants enter the roadhouse. The man slips out of his car and enters the other vehicle. A little rewiring and the car is driven off. Several miles down the road the stolen car is met by another automobile.
The driver of the second vehicle pulls an unconscious man from the back seat. He holds the man up and signals to the stolen car. The stolen auto speeds down the road and at the right moment the unconscious man is dropped in front of it. The stolen car is then returned to the roadhouse lot. Twenty minutes later the police enter the roadhouse looking for the car's owner. The police put the pinch on the owner and haul him away.
They inform him they have received a report from a concerned citizen about a hit and run. The young man pleads his innocence but the evidence matches his automobile. The young man needs help. In steps "Richard Diamond, Private Eye." Diamond (David Janssen) agrees to look into the matter.
He begins by staking out the so-called "concerned citizen." He soon discovers that the man is a mobster who does a little free-lance work as a hit-man.
Janssen sends Nick Dennis, one of his underworld contacts, to arrange a hit. The target? Janssen himself. Dennis gives the hit-man the time and place for the hit. Janssen then contacts the police who join him in setting up a sting operation.
There is a small problem with Janssen's plan, however: neither Janssen nor the police know about the hit-man's partner! The pair strike early and grab Janssen before he reaches the arranged location for the hit. They tell Janssen they are all going for a little drive in the country. The pair plan to eliminate Janssen the same way as their last victim.
One of the killers is dropped off to secure a car. The other thug sticks a gun in Janssen's ribs and tells him to drive. The police waiting at the stakeout soon realize something is amiss when Janssen does not show. They put out a all-points for Janssen and his vehicle.
Janssen and the second killer have reached the spot for Janssen's unfortunate coming accident. The police however arrive in the nick of time and with guns blazing save the day. One killer is dispatched and the other captured. The young man in jail is cleared and the case closed.
Neat little episode!
And, as a bonus, here is a link to a video with the constantly-adjusted opening theme song to RICHARD DIAMOND, a show that bounced around different networks during its four years of hardscrabble existence. Diamond even changes coasts (NYC to LA) during the course of the show's run.