To pass the time, Walt built a prototype "Crime Computer" hidden in a large stone sarcophagus near an exhibit of legendary monsters.
When Walt plugged in his computer, "oscillating vibrations" brought to life the wax statues of Dracula (Henry Polic II), the Wolfman (Buck Kartalian) – who here was named "Bruce W. Wolf" (with one episode revealing that the "W" stood for "Were") – and the Frankenstein Monster (Michael Lane), who was referred to as "Frank N. Stein" in the credits.
The gentle giant Frank, for example, possessed superhuman strength and could smash through walls, while the dapper cloak-clad and fearsome-fanged Drac could turn into a bat, and the short and furry Bruce was a ferocious fighter who could climb up the sheer sides of buildings Spider-Man-style and had a super-sensitive sense of smell.
The villains were often exaggerated camp supervillains much like the ones on Batman in keeping with the "superhero" tone of the show, and were often played by familiar-faced guest stars of the time, like Alice Ghostley ("Queen Bee"), Marty Allen ("Lorenzo Musica"), Jonathan Harris ("the Astrologer"), Julie Newmar ("Ultra Witch"), Avery Schreiber ("the Weatherman") and Vito Scotti ("Albert/Alberta").
A later, unrelated animated television series by Hanna-Barbera Productions called Drak Pack had a similar premise, as did the DC Comics characters the Creature Commandos, although they fought Nazis rather that super-criminals.