A scientist develops a serum from fruit flies that allows the body to increase its adaptive abilities so that it can fight disease. When he tests it on a woman with a fatal illness, she not only recovers but becomes evil and murderous.
Stanley G. Weinbaum may well have been the best science fiction author of the thirties; his "A Martian Odyssey" is rightly considered one of the great science fiction short stories of all time. Unfortunately, he died in 1935, and this movie is to date the only cinematic adaptation of any of his works, specifically of his story "The Adaptive Ultimate". It's been years since I read that story, but I do remember the immense charm of his work; that charm is to be found nowhere here. Instead, it takes the central idea and surrounds it with the usual collection of science fiction cliches of the era, particularly that of scientists tampering in God's domain and thwarting the wishes of the almighty. This is not to say these cliches don't have a charm of their own; it's just sad that the only movie adaptation of his work totally fails to do him justice (though there may be more successful TV or radio adaptations out there somewhere). On the plus side, Mari Blanchard is quite attractive, it's always fun to see Albert Dekker, and the central special effect (a woman's hair changes color before our eyes) is well done. On the down side, it's lethargically directed, indifferently paced, and puts forth its cliches without any sense of subtlety or creativity. Fans of low-budget science fiction movies of the era will probably like it; Weinbaum fans would be better off rereading his stories.