Dr. Paul Carruthers is a scientist who designed a perfume for a company, then sold off his shares. This cosmetics company made his partners a fortune. Carruthers, out of a misplaced sense of revenge, decides to experiment on a bat to make it large and ravenous. He then conditions it to kill anybody wearing a perfume he designed and gave to his enemies as a seeming gift.
Two sequels have been released, Devil Bat's Daughter in 1946 and Revenge of the Devil Bat in 2015.
This film contains examples of:
- Antagonist Title: Referring to the nickname the press gives the giant bats.
- Bat Out of Hell: Dr. Carruthers has a giant bat he uses to kill his enemies.
- Big Bad: Dr. Paul Carruthers, master of the Devil Bat.
- Honest Corporate Executive: Despite Carruthers' claims, Heath and Morton are perfect to honest, having given him the option of joining the company or selling off the stocks. Even after Carruthers chose the latter, they gave him a check for $5,000—equivalent to $87,000 today—as a show of gratitude.
- Lightning Can Do Anything: Electrical impulses can make bats grow exponentially.
- Omnidisciplinary Scientist: Carruthers does work in medicine (town doctor), chemistry (designing perfumes), biology (experimenting on the size of bats) and psychology (conditioning bats to react violently at certain scents).
- The Sociopath: Dr. Paul Carruthers, who makes giant bat monsters to kill the corporate executives he sold his makeup formulas to, and their entire families, because he didn't believe he got enough credit despite the fact that they were completely upfront with the fact that they'd be using it for profit.
- Villain Opening Scene: Carruthers finishing his bat growth experiments.
- Villain with Good Publicity: Dr. Carruthers is a vengeful murderer with a reputation as a kindly small town doctor.