O'Hara, U.S. Treasury starred Janssen, whose company co-produced the show with Mark VII, as the title character, Treasury Agent Jim O'Hara. A county sheriff from Nebraska whose wife and child died in a fire, O'Hara cut all ties with his past life. He takes the Treasury Enforcement Agent exam and puts in an application with the United States Department of the Treasury, Secret Service. He is offered a position as a Special Agent with the Customs Service. He accepts the offer. He is assigned to a Customs office on the U.S.-Mexico border. His first case requires him to go undercover to break up a large narcotics smuggling organization. His abilities as an undercover agent become apparent to his bosses.
O'Hara marked the first Mark VII show to run a full hour in length; all of Webb's previous efforts (excepting the TV-movie pilot for Dragnet 1967) ran in half-hour episodes. It was also one of the few he did not package for NBC. The show failed to compete in the Nielsen ratings against ABC's The Partridge Family and Room 222 and ended after one season, ranking 48th out of 78 shows with an average 17.1 rating.[2] Reruns were later shown on the A&E Network in the 1990s and on Retro Television Network in the 2000s.[3]
According to Brandon Tartikoff, when Fred Silverman was the head of programming at CBS and considering whether or not to renew O'Hara, he met with a representative of the Treasury Department, who told him, "There are those of us down in Washington who like the idea of a weekly prime-time showcase. So if the show gets cancelled, we're gonna do what we've gotta do." Silverman didn't take the Treasury representative seriously, but according to Tartikoff, after the show was cancelled, "about a dozen top CBS executives on both coasts had their income taxes audited the following year."[4]