The show's title had a double meaning: it was at once the first name of the lead character, Chase Reddick (Mitchell Ryan), the leader of a special team of the Los Angeles Police Department that specialized in solving unusually difficult or violent cases, and indicative of the show's emphasis on the determined pursuit and undercover surveillance of hardened criminals.

The unit, headquartered in an old firehouse, relied mainly on alternate/undercover means of transportation such as helicopters, motorcycles, custom vans, taxis, four-wheel-drive vehicles, sports and muscle cars, work trucks (vehicles from the Public Works Department, the telephone company, tow trucks and/or the Postal Service and civilian delivery services) and high-speed driving to apprehend its suspects.

For the first fourteen episodes, Reddick, an LAPD captain, was accompanied by K-9 Sergeant Sam MacCray (Wayne Maunder) and three young officers: Steve Baker (Michael Richardson), Norm Hamilton (Reid Smith), and Fred Sing (Brian Fong).

In January 1974, Webb and Universal dropped all the regulars except Ryan and Maunder in favor of a new group of officers: Frank Dawson (Albert Reed), Ed Rice (Gary Crosby, who frequently appeared on the other Mark VII shows), and Tom Wilson (Craig Gardner).

Never seen, but "appearing" in every episode was actual LAPD dispatcher Shaaron Claridge, who had worked on Dragnet and Adam-12; according to the pilot script, she was assigned especially to Chase.