The original director/actor team for Universal's FRANKENSTEIN (1931) was initially announced as being Robert Fleming and Bela Lugosi when suddenly the studio turned the whole project over to James Whale and it took a different direction.
The team was assigned MURDERS IN THE RUE MORGUE so we get a glimpse as to what might have been had they gotten the original gig.
Set in Paris in the mid nineteenth century and based loosely on the story by Edgar Allan Poe this movie goes into territory the novel never explored and it's amazing that it made it by the censors.
Bela Lugosi is Dr. Mirakle-- a circus sideshow barker who displays his captured ape ERIK for any who want to see the mysteries of the rest of the world. There is a little more to the relationship however, as we see Lugosi convinced he can both talk to and understand what the ape is trying to communicate. Mirakle has a pretty interesting idea-- if he can mate his gorilla with a young woman he'll have something more than just a sideshow curiosity. He begins kidnapping women and tying them to a giant cross in his laboratory and injecting them with ape blood to see the results.
It goes on from there, and many of the most horrific aspects of Poe's original make it into the film version. Something that could have never happened with the self censorship of Hollywood which began in the mid thirties.