Surprisingly effective and atmospheric Mexican horror film directed by Chano Urueta, which mixes elements from every story featuring a mad scientist or a woman falling in love with the wrong man, with a bit of Fritz Lang's "M". However, it takes above anything else the basic premise of "The Miraculous Serum" (1952), first adaptation of Stanley G. Weinbaum's short story "The Adaptative Ultimate", made for the TV series "Tales of Tomorrow". It was remade twice, first -again for television- as "Beyond Return" (1955) for the series "Science Fiction Theatre", and two years later as the feature "She Devil", in which Mari Blanchard played a brunette with TB who was turned into a lethal and invulnerable blonde. There is a big difference, though: after "The Witch" (called as such because of her extremely ugly face) is injected with the serum, turned into a beautiful woman, and educated and polished to pass as a rich countess (Lilia del Valle), she remains emotionally vulnerable. She has to kill three business men who supposedly wronged a scientist (Julio Villarreal), but she falls for the young, dashing Fedor (Ramón Gay), leading the story to tragedy, when all the marginal and handicapped men and women from the underworld (as in "M") create their own court of justice
It is funny how in these strange Mexican fabrications, names and locations from Eastern Europe are candidly mixed with native elements, and in the end get away with it. Perhaps that is one of the reasons why many of them are so fascinating, including others directed by Urueta, as "El monstruo resucitado", "El espejo de la bruja" and "El barón del terror".