For 20 years, unrepentant Nazi scientist Dr. Norberg, Dana Andrews, has been thawing frozen Nazi soldiers kept in suspended animation at his English country estate since the end of World War II. He awaits orders from his superiors, General Lubeck and Captain Tirpitz, who have been told by Norberg's assistant Karl Essen, Alan Tilvern, that Norberg's experiments have been a complete success. Unfortunately, they have not. Norberg can thaw the bodies but not the brains, yielding zombie-like beings who can only replay a single past action. The most dangerous of them is Prisoner no. 3, Norberg's brother, a violently unstable presence who embodies the darkest flaw of the project.
To move the scheme forward, Norberg enlists American scientist Dr. Ted Roberts, Philip Gilbert, who has had some success thawing functional brains. Ted, unaware of the deeper Nazi plot, believes he is assisting Norberg in keeping organs alive for medical research. The widening mystery pulls in Norberg’s family circle and the curious outsiders around him, setting a fever pitch of secrecy, fear, and ambition.
Norberg’s niece, Jean Norburg, Anna Palk, returns home from America with her friend Elsa, Kathleen Breck (Elsa Tenney) in tow. On the day after, Jean is told Elsa left for London on the 6:00 AM train, though Jean cannot quite understand why her friend would disappear so abruptly. Norberg then confides in Ted about a gruesome plan to test the limits of life by experimenting on an ape’s head, watching its brain through a transparent dome, and eventually transferring what is learned to a human. Ted agrees, but the real danger arrives when Karl drugs Elsa and brings her to the lab instead of the train station, leaving Norberg and Ted to confront a brutal, living horror: Elsa dead in the lab, and Prisoner no. 3 smiling over the body.
Norberg’s unsettling demonstrations grow more elaborate after he shows Ted a wall of amputated human arms, each controlled by electrical stimulation. Ted, now complicit in the danger, agrees to keep silent about what he has witnessed. Norberg then reveals Elsa’s head—alive, its blue-tinged skin stretched over a brain encased in a clear plastic dome—and Ted recoils from the terrifying possibility that the mind behind the dome could guide the rest of the project.
That night, Jean experiences a nightmare in which Elsa seems to speak from beyond the grave. She tells Ted that Elsa is not just a corpse but a conduit of something supernatural, and Ted reluctantly dismisses the dream as a trick of the mind. In truth, Elsa has begun to communicate telepathically with Jean as she sleeps, and Jean—unaware of the full truth—begins a desperate search for her friend. She consults railway personnel and a Mrs. Schmidt, Anne Tirard, who appears to know nothing about Elsa, though she is involved in darker undercover work. Jean then turns to the police, asking Inspector Witt, Tom Chatto, to investigate.
The plot thickens once more when Karl is knocked unconscious by an intruding force, and Norberg admits that Elsa’s head can still influence the lab’s experiments—but only if the will behind it is strong enough. Jean’s fear grows as she senses a looming threat to those around her, including Ted. Karl’s loyalty to the Nazi cause becomes a point of brutal torture by Lubeck and Tirpitz, who pressure him for information about who has learned what. By promising punishment, Norberg compels Karl to reveal that the Schmidts—who are connected to the underground Nazi network—may hold the key to Elsa’s true power.
As the plan escalates, Elsa makes a more dramatic claim: she can control the wall of arms, bending them to her will, though Norberg scoffs at the possibility. Ted, however, suggests that Elsa still possesses willpower, a crack in Norberg’s certainty that the experiment has proven true efficiency. The leadership duo, Lubeck and Tirpitz, grow increasingly afraid that Jean will uncover the entire scheme, and they discuss eliminating Jean as a danger.
That night, Elsa communicates again with Jean, and Jean, guided by a trance, heads toward the lab. Ted wakes her at the locked door, and Jean insists that Elsa must be saved. Ted explains that no. 3 is actually Jean’s father, and a painful realization follows: no. 3 killed Elsa, but Elsa later reveals the truth that Karl killed her. Lubeck finally discloses the Nazi plot to Jean, drawing a pistol in a tense confrontation. In the struggle that follows, Elsa activates the arms, and they begin to strangle Lubeck and Norberg in front of the writhing wall.
Jean rushes to reach her father as Tirpitz arrives just in time to shoot Prisoner no. 3 before he can harm Jean. The climactic struggle ends with Elsa whimpering a soft, sorrowful plea—“Bury me”—as she acknowledges the toll of the events around her. In the aftermath, the survivors—Jean, Ted, and Witt—stand over Elsa’s poignant last word, confronted with the price of a science that sought to push life beyond ethical boundaries and into a nightmare where memory, mind, and body can no longer be kept separate.
