Karutha Rathrikal is a 1967 Indian Malayalam-language science fiction film directed by Mahesh. An adaptation of the novella Strange Case of Dr Jekyll and Mr Hyde by Robert Louis Stevenson, it was the first science fiction film in the history of Malayalam cinema.
Santhan, a medical practitioner, is in love with his uncle's daughter Vimala; their marriage is fixed. Vimala's father was a banker who died under mysterious circumstances. Santhan develops a medicine, which turns a person into a monster when consumed. He also invents the formula that reverts the person back to their original self. Santhan keeps this invention a secret. From his uncle's diary, Santhan learns that other greedy directors of the bank are responsible for his death. Santhan decides to take revenge on them by utilising his invention.