Peppard played Thomas Banacek,[2] a Polish-American freelance, Boston-based private investigator who solves seemingly impossible thefts.

[3] Murray Matheson plays seller of rare books and information source Felix Mulholland, a character always ready with a droll remark and who exhibits a passion for chess and jigsaw puzzles.

An unapologetic ladies' man who enjoys the company of beautiful women, he is also street-smart and can engage in hand-to-hand combat when the need arises; in one episode he mentions having learned combat judo in the Marine Corps, which is probably a reference to George Peppard's two-year enlistment in the Marine Corps, being discharged at the rank of Corporal.

In keeping with both the exotic car theme and the humor between Banacek and his driver Jay Drury, he was even chauffeured around in a Willys MB, Jeep CJ2A,[8] and a CJ6,[9] as well as a brand new Ford/De Tomaso Pantera.

In the pilot, Banacek's car pulls into his Beacon Hill home, the historic Second Harrison Gray Otis House located at 85 Mount Vernon Street.

In other episodes, views are shown of the Public Garden, the entry to Felix's bookstore at 50 Beacon Street, and the Esplanade.

However, before the third season could start, Peppard quit the show to prevent his ex-wife Elizabeth Ashley from receiving a larger percentage of his earnings as part of their divorce settlement.

The character Banacek was also referenced in The Simpsons "Treehouse of Horror III" segment "Dial Z for Zombies" when Bart tries to cast a spell to rid Springfield of the zombies he unleashed by intoning the magic words "Kojak, Mannix, Banacek, Danno..." (All names of 1970s TV detectives.)

In 2018, Banacek was the subject of an episode-length parody in The Simpsons ("Homer Is Where the Art Isn't"), with Bill Hader voicing the Peppard character, named "Manacek".

The episode is patterned closely after a typical Banacek outing, referencing items from the series' storytelling format to its establishing shots.

"[16] Banacek has a clear resemblance to the title character of the Steve McQueen movie The Thomas Crown Affair, particularly in his attitude towards women and authority.

On September 30, 2008, Arts Alliance released Banacek: The Complete Series, a five-disc box set featuring all 17 episodes.