If the presence in The Mad Monster of George Zucco, Anne Nagel, and Glenn Strange may cause a viewer to, if only briefly, mistake this slapdash production for a Universal horror film -- after all, the trio appeared in quite a few Universal potboilers and the latter even played Frankenstein on three occasions -- the fogbound and moss-covered sets are unquestionably parsimonious PRC. But, as with the later and better-regarded, but not necessarily better, The Strangler of the Swamp (1945), the claustrophobic feeling of a small sound stage actually adds to the film's ambience. Zucco was PRC's resident boogeyman and his hammy way with a line actually becomes an asset in this and a few other shockers like it. And if Zucco was a poor man's Boris Karloff (or Lionel Atwill or even Bela Lugosi), Glenn Strange made no bones about imitating Lon Chaney Jr.'s fine Lenny in Of Mice and Men (1939) -- to the point where Chaney would rip him mercilessly whenever the two friends met. Neither Zucco nor Strange would win any awards for their performances here, but they never fail to hold your interest. Miss Nagel is quite all right, too, in her limited role, and although he certainly doesn't deserve star billing, Johnny Downs is mostly painless as the typical "gee whiz" Hollywood reporter. In fact, everyone involved with The Mad Monster, including director Sam Newfield, had done worse.