Strange crimes ripple through Cornwall, shaking a quiet coastal town. Doctors' surgeries are burgled, and residents vanish, leaving investigators puzzled. The stolen medical supplies point to something far more sinister: a hidden lab secretly set up in the disused Porthcarron Tin Mine, where captives are immobilised and hauled away.
Dr. Peter Blood, Kieron Moore, a young doctor returning to his hometown after a biochemistry grant in Vienna, arrives at the center of the mystery. His father, Dr. Robert Blood, is the village physician, and he is joined by Linda Parker, a young widowed nurse who assists Robert Hazel Court. As the crimes unfold, Police Sgt. Cook, portrayed by Kenneth J. Warren, leads the investigation into the disappearances and the suspicious activity around the mines.
Peter eagerly volunteers to help search for the latest missing man, George Beale, but his real aim is darker: he fears discovery of the mine lab and the illegal work he himself has begun. In the mines, Beale is found crawling away, nearly succumbing to whatever force has him, and Peter’s actions escalate quickly. He injects Beale and proclaims him dead, offering to perform the post mortem, while Robert struggles to decipher a broken syringe found in Beale’s room. Linda discovers a curious clay container, which Peter explains away as a gift from school days—an ancient South American curare container.
In conversation with Linda, Peter swirls memories of Vienna, insisting that he and his supervising professor were on the verge of a groundbreaking discovery that was abruptly halted by a rule-bound, ignorant rival. He boldly declares that “no one's going to hold me back now.” The tension intensifies as Beale’s planned PM moves forward in the village mortuary owned by Mr. Morton, but Beale is not dead. Peter resumes the grisly work, arguing that Beale was worthless and that he will transplant Beale’s heart into someone who deserves to live. When Morton interrupts, Peter’s temper erupts and he inadvertently kills Morton, sealing Beale’s fate as Beale’s heart dies too.
Back in town, Peter escorts Linda to the tin mines again, spinning a strange tale from his childhood about pretending to be dead and returning to life. They are interrupted by self-employed tin miner Tregaye, who becomes Peter’s latest victim. At Beale’s funeral, Linda notices her husband Steve Parker’s grave and feels a growing unease about the doctor she has come to trust.
Robert returns from Plymouth Hospital with a critical clue: the syringe’s liquid is curare. Peter works to deflect suspicion, claiming that he and Linda had been discussing curare—yet Linda’s suspicions deepen. Sgt. Cook arrives to report that Tregaye has been found, but not dead; the curare has immobilised him.
A confrontation unfolds as Linda challenges Peter’s philosophy. He argues that he has the power to decide who lives or dies, a claim she rejects by invoking God’s authority over life and death. “Only God has the right to decide who lives and dies,” she insists, while Peter contends that restoring “physical life” could yield an evil being.
As the net tightens, Sgt. Cook and Robert realize Peter’s guilt. Peter visits the cemetery, digs up a body, and brings it to his lab where he transplants Tregaye’s heart into the reanimated corpse—Steve Parker. A city-wide search is launched, but the scientist’s plan accelerates: Peter forces Linda into the mine, where she encounters the decomposed—but living—Steve. The reanimated Steve attacks Linda, and a brutal struggle ensues. Peter is killed by Steve in the confrontation, and Steve dies again, leaving Linda to flee to the shoreline where a search party arrives and she is finally safe.
This tale blends scientific ambition, moral peril, and a creeping horror, examining the line between healing and harm and the dangerous temptations that can arise when a physician believes he alone can decide who deserves life.
