The show concerned the shenanigans of a group of anthropomorphic cats living in Hoagy's Alley (based on the real-life classic comic strip "Hogan's Alley") somewhere in Midtown Manhattan. The gang was usually involved in some whacky get-rich-quick scheme. Most of them turned inside out and upside down leaving the gang just as penniless as before.
The cats included the clever boater and waistcoat-wearing Top Cat ("T.C."), who was the "indisputable leader of the gang" as the show's catchy theme song made clear. Top Cat's character was based on that of Sgt. Bilko, Phil Silvers character from The Phil Silvers Show.
Top Cat's right-hand-cat, Benny The Ball, was a short, rotund cat who wore a white jacket. Rather innocent and easily confused, he, ironically, generally managed to be the most logical of the group. Benny The Ball was based on Doberman, a character from The Phil Silvers Show, and was voiced by Maurice Gosfield, who had played Doberman.
The Brain was the slow-witted treasurer of the gang, which may be one reason they rarely had any money. Generally lost in a fog bank, The Brain nevertheless could manage to come up with an occasional brilliant idea, usually just in time to get everyone out of trouble.
Fancy-Fancy spoke like the actor Cary Grant and wore a dashing white silk scarf. A ladies' cat, and a cat of some refinement, he was usually able to charm his (and the group's) way out of sticky situations.
Spook had a bit of Greenwich Village in him, "like, eh, like dis, yeah, man," and resembled Fancy-Fancy but had Choo-Choo's penchant for games of chance.
The gang's nemesis was Officer Charlie Dibble, usually referred to (to his face) by T.C. as "Dibble, baby!" who habitually threatened to "run them in" as confidence cats, but Dibble frequently allied with them against outside troublemakers too.
The show drew from many elements --- especially The Phil Silvers Show, The Dead End Kids, The Honeymooners, and West Side Story, among others --- and there was a strong element of New York street smarts, beatnik culture, and 1950s jazz music in the program as well.
Although it only ran one season, it is eminently memorable, and New York urban slang still retains the word "Dibble" for a police officer, rarely heard but still remembered.