Description
American foreign news correspondent Larry Stanford (Dyneley) has been working in Japan for the last few years, to the detriment of his marriage. His last assignment before returning to his wife in the United States is an interview with the renowned but reclusive scientist Dr. Robert Suzuki (Tetsu Nakamura), who lives atop a volcanic mountain. During the brief interview, Dr. Suzuki amiably discusses his work on evolution caused by sporadic cosmic rays in the atmosphere, and professes that he has discovered a method for producing evolutionary change by chemical means. Suzuki serves Larry a secretly drugged libation, causing him to fall into a deep sleep. Announcing to Tara (Terri Zimmern), his voluptuous assistant, that Larry is the perfect candidate for his latest evolutionary experiments, he injects an unknown substance into Larry's shoulder. Upon waking, Larry is oblivious to the true situation and accepts Suzuki's invitation to spend the next week vacationing with him around Japan. Over the next few days, Suzuki uses Tara as a beguiling distraction while conditioning Larry with mineral baths and copious amounts of alcohol, exacerbating the pain in Larry's shoulder.
Meanwhile, Larry's estranged wife (Jane Hylton) has traveled to Japan to bring him back home with her. When confronted, Larry refuses to leave his new life of women and carousing. After a few drinks that night, Larry examines his painful shoulder to discover that a large eyeball has grown at the spot of Dr. Suzuki's injection. Becoming aloof and solitary, Larry wanders Tokyo late at night. He murders a woman on the street, a Buddhist monk and a psychiatrist, while slowly changing form, culminating in his growing a second head. Seeking a cure, Larry climbs returns to Dr. Suzuki's laboratory, where Suzuki has just informed Tara that Larry has become "an entirely new species" and is beyond remedy. Entering the lab, Larry kills Suzuki and sets the building on fire as Tara flees. Following her to the rim of the volcano, Larry splits into two completely separate beings, one looking like his normal self, the other animalistically grotesque.
The monstrous second being grabs Tara, and throws her into the volcano. As Larry's wife and the police arrive, Larry pushes his other self into the volcano. Larry, in a state of collapse but returned to normal, is taken away by the police, although it remains unclear how much moral or legal responsibility he has for his violent actions. The movie ends as Larry's wife and the police superintendant discuss the good that remains in Larry.
