Dr. Lorenzo Cameron is a discredited - and quite mad - medico who has discovered a way to turn his gardner, Petro, into a wolf man. The lycanthropic experiments succeed only too well, and although Dr. Cameron spouts plans of turning his discovery into a weapon in defense of the civilized world, he instead unleashes his creation on those fellow scientists who had engineered his ouster from academia in the first place.

Before long, however, the good doctor is unable to control the wolf man, who threatens to kill everything in his path. Only newspaper reporter Tom Gregory and Lenora, Cameron's innocent daughter, may be able to stop the monster.

For the ''MysteryScienceTheater3000'' version, please go to the [[Recap/MysteryScienceTheater3000S01E03TheMadMonster episode recap page]].

!!Tropes appearing in this film:
* DidntThinkThisThrough: Averted. Dr. Cameron wants to turn his already hulking gardner into a murderous monster; how are you going to control it? Simple; the doc has the antidote at hand.
* ForScience: In step with other "monster/mad scientist" films of this vintage.
* HeyItsThatGuy: Johnny Downs (of [[TheLittleRascals Little Rascals]] fame) as TheHero, Tom Gregory
* HoistByHisOwnPetard: Also in keeping with genre standards.
* ImmuneToBullets: Cameron's werewolf serum somehow gives Petro some tough skin armor.
* InfantImmortality: Averted, but thankfully off screen; we only hear words to this effect afterward.
* IntrepidReporter: Tom Gregory
* KillItWithFire: A [[ContrivedCoincidence very handy]] lightning strike does the work for us.
* KindheartedSimpleton: Petro really wouldn't hurt a fly... except under the influence of Dr. Cameron's lycanthropy cocktail, which he remembers only as a bad dream. And then the violent feelings begin affecting him even when he's "normal"...
* MadScientistsBeautifulDaughter: She wants to be JudyGarland in the worst way.
* TheMockbuster: Following hot on the heels of the previous year's ''Film/TheWolfMan1941'' from [[UniversalHorror Universal Studios]].
* [[NotUsingTheZWord Not Using The W Word]]: Only the superstitious old woman in the cabin uses the term "werewolf", although Cameron does call Petro a "wolf man".
* RedHerring: The superstitious old woman keeps telling everyone within earshot that you can kill a werewolf only with a silver bullet. This never comes into play, though mainly because no one believes it's a real werewolf (and, in most respects, it isn't).
* ReedRichardsIsUseless: Played With. Dr. Cameron does mention that the military could create nigh-unstoppable werewolf armies with his lycanthropy formula (and control said armies with the antidote), but right now he's just using it as a tool of revenge.
* RoaringRampageOfRevenge
* ShadowDiscretionShot: Dr. Cameron's ultimate demise by werewolf is depicted thusly.
* TheseAreThingsManWasNotMeantToKnow: Academia's reason for Dr. Cameron's ouster.
* TheyCalledMeMad: Gee, Doc, and your [[EvilLaugh maniacal cackling]] and tendency to talk aloud to figments of your imagination did '''nothing''' to convince them otherwise? Really.
* UnwittingPawn: Petro