Hammer had already made two adaptions of Robert Louis Stevenson’s Strange Case of Dr. Jekyll and Mr. Hyde — The Ugly Duckling and The Two Faces of Dr. Jekyll. But what if they combined that story with the historical Jack the Ripper and Burke and Hare cases? And what if Jekyll turned into a female Hyde? Now we have a movie!

Dr. Henry Jekyll (Ralph Bates, Lust for a Vampire) has been trying to cure all known illnesses but his friend Professor Robertson (Gerald Sim, Dr. Phibes Rises Again) laughs that by the time his experiments are discovered and used, he’ll be long dead and unable to enjoy his achievements.

Jekyll then abandons his altruistic aims and starts looking for the elixir of life, which he feels uses female hormones that he takes from the bodies of women supplied by William Burke and William Hare, real life murderers that killed people and sold them to doctors for anatomy lessons. Never mind that those murders happened sixty years before the timeline of this film.

Meanwhile, Susan Spencer lives above him and they’re attracted to one another. However, he’s too absorbed by his work to do anything about it. Soon, he’s created a serum that not only changes his character, but transforms him into a gorgeous and amoral woman (Martine Beswick, who is in the first two Bond movies, plays the Queen of Evil in Seizure and was Xaviera Hollander in The Happy Hooker Goes to Hollywood) that he calls Mrs. Edwina Hyde. Susan instantly hates her, but her brother Howard (Lewis Fiander, Who Can Kill a Child?) falls for her.

Dr. Jekyll soon learns that his serum requires more female hormones than Burke and Hare can acquire for him. And when they’re finally caught, he’s forced to commit the crimes that the rest of London believes were those of Jack the Ripper. Jekyll hates what he has become, but Hyde loves it, even killing the Professor when he dares question her.

The male and female sides of his/her/its body all go to war with one another with Susan as the prize. Seriously, this is a movie that demands to be remade today.

Sadly, Caroline Munro was nearly Mrs. Hyde, but dropped out when she realized that the film required nudity. That said, Martine Beswick is pretty great in this. She was initially asked to do full frontal nudity and wouldn’t talk to director Roy Ward Baker (Asylum, The Vault of Horror) for a week.