On a late-night drive toward Montreal, Martin Delambre encounters a young woman, Patricia Stanley, running in her underwear. They fall in love and marry, but both carry secrets: she has recently escaped from a mental asylum, and he, along with his father, Henri Delambre, is immersed in radical teleportation experiments that have already yielded horrific consequences. Martin also harbors recessive fly genes that cause him to age rapidly unless he takes a special serum.
Set in a rambling mansion in rural Quebec, the Delambres have achieved teleportation between the estate and London, yet previous attempts have produced disfigured, insane victims locked up in the stables. Among them is Martin's first wife, Judith Delambre, as well as Samuels and Dill, two former assistants. Albert Delambre runs the London receiving station but longs to terminate the project and escape the obsession that has gripped his grandfather, his father, and his brother. Wan and Tai, a Chinese couple who work in the house and the lab, complete the household and keep the operation running.
The police and the headmistress of the asylum trace Patricia to the Delambre estate and learn that she has married Martin, but they soon discover that he had a previous wife who was never divorced. Inspector Charas, who had investigated Andre Delambre, shares the family history with Inspector Ronet as they discuss the Delambres’ dangerous experiments.
As the net tightens, a mix of callousness and madness spreads through the Delambre clan, and they resolve to abandon their work and erase the evidence of their failures. They subdue and plan to teleport Samuels and Dill to the London lab, but Samuels awakens and launches an attack on Martin. With the aid of Henri, who seems to ski`p in to help his son, they manage to stop Samuels. Unable to reach Albert, they teleport one of the assistants anyway. When they finally reach Albert, they realize the two assistants would reintegrate into a single writhing mass, an gruesome sight that horrifies him. Albert responds instinctively and kills the writhing mass with an axe.
Wan, angry about what happened to Judith, sometimes releases her so that Pat can glimpse her, but Martin and Henri insist it’s only a nightmare. Yet Martin admits the truth when Pat begins to fear she is insane. Wan releases Judith again, informing her that Pat is in Judith’s bedroom, but Judith locks Wan in a cell and goes after Pat. Pat races to the lab, where Tai is working; as Pat escapes, Judith attacks Tai, who kills her in self-defense. Tai releases Wan and explains what happened, and the two teleport Judith’s body to avoid a potential murder charge. Yet Tai and Wan have had enough and depart the Quebec estate.
On their return from another interview with the police, Henri persuades Martin that they must send the unconscious Patricia to London and then follow to evade the authorities. Martin resists, but Henri volunteers to go first. Martin sends Henri to London, unaware that Albert Delambre has destroyed the reintegration equipment and that Judith was sent without his knowledge beforehand, an action that could have caused another cell merge if Albert hadn’t sabotaged the machine. Henri does not rematerialize and is lost. Realizing what happened, Albert collapses in grief and disappears from view.
Inspector Ronet arrives at the estate, passing Tai and Wan as they drive away. Patricia awakens in the teleportation chamber but escapes before the transmission completes. Martin pursues her, but aging accelerates again; without his serum he dies, sprawled across the front seat of his car. Soon after, Ronet finds him reduced to a skeleton and escorts the shaken Patricia back into the house.
