The Astounding She-Monster is a 1957 science fiction horror film starring Robert Clarke and directed, written and produced by Ronald V. Ashcroft. The film focuses on a scientist and a gang who have kidnapped a rich heiress and their encounter with an alien who has crashed to Earth. In the UK, it was released as Mysterious Invader. It was released by American International Pictures as a double feature with The Saga of the Viking Women and Their Voyage to the Waters of the Great Sea Serpent.
A group of criminals who have kidnapped an heiress take over a geologist's home in a secluded forest to hide in. Then a UFO crashes nearby and out emerges an alien resembling a beautiful woman- however, she's highly radioactive and can kill with her bare touch. She starts stalking and killing the other characters. In the end, the alien herself is killed, but not before the scientist realizes she was only trying to ask for help, apparently unaware of how dangerous she was to humans. He fears what the reaction of her race will be towards Earth after the incident.