Tonights's Awful Bedtime Movie: Mad Monster (1942)
If any movie obeys Bad Monster Movie Law to the letter, it's "Mad Monster."
Dr. Lorenzo Cameron's colleagues consider him crazy, so he decides to prove them wrong -- by turning his gardener into a werewolf that kills them. Monster Movie Law is obeyed as 1) an unwilling assistant in turned into the monster, and 2) through the use of a "serum."
In compliance with Bad Monster Movie Law, the villain develops the monster to 3) exact revenge against colleagues who consider him crazy.
Well, technically they didn't call him crazy.
At some point in the film Cameron has an imaginary conversation with his colleagues where he tells them he developed a serum that turns America's soldiers into wolfmen so they can fight the Communist menace. The imaginary versions of his colleagues laugh at him, so logically he decides to instead use the serum to kill his real-life colleagues.
Finally, in compliance with Bad Monster Movie Law, the case is cracked by 4) a reporter the female lead has fallen in love with, and 5) the mad scientist and monster die in a laboratory fire.
From what I've seen on film, in the 1940s and 50s laboratory fires killed more people than heart disease and cancer combined.
What I Learned Today: When applying for a job as a low-level employee of a scientist who lives in a rural mansion always ask A) for a no-injection-of-serums clause, and B) where the fire extinguisher is.