The Fly

In Montreal, scientist André Delambre is found dead, his head and left arm crushed in a hydraulic press. The investigators are perplexed, and his wife Hélène confesses to the crime but refuses to provide a motive. She also begins behaving strangely, especially around flies.

Hélène confesses to the murder but cannot explain her motive. Soon afterward, she becomes obsessed with flies, including a supposed white-headed variety. The strange behavior unsettles everyone around her.

André's brother François lies and claims he caught the white-headed fly to mislead the investigators. His deception hints at a more complicated truth behind the death. The tension between truth and secrecy begins to complicate the case.

Believing she knows the truth, Hélène asks François to bring Inspector Charas so she can explain the circumstances to both of them. She hopes the inspector will confirm her account and expose the motive behind André's death. The stage is set for a confrontation that blends present reality with past events.

In a flashback, André, Hélène, and their son Philippe appear as a loving family. They live with a secret curiosity in a basement lab where André works on a matter-transporter device. The atmosphere is bright and hopeful as the project seems within reach. The family dynamic contrasts with the looming danger of the experiment.

André works on the disintegrator-integrator, testing the device on small, inanimate objects. He documents careful progress as the apparatus seems to disassemble and reassemble matter with surprising fidelity. The science is exciting, but the stakes feel increasingly personal.

After initial success with objects, André extends tests to living creatures. The family's cat is the first test, and it fails to reintegrate, though its meows can be heard somewhere in the house. A guinea pig is next, and the results remain uncertain.

Buoyed by progress with small tests, André builds a full-scale pair of chambers capable of transporting a human. He envisions using the device to explore new frontiers of science. The setup marks a turning point from experiments on toys to experiments on life.

One day, André tries to transport himself, but a fly is trapped in the chamber as well. The atoms mix so that the fly gains André's head and left arm while André retains his mind but with a fly's features. He communicates by typed notes and knocking, revealing the terrifying fusion.

Knowing time is running out, André asks Hélène to capture the fly so he can reverse the mutation. The family and their housemaid search tirelessly through the house for the creature. The fly eventually slips out of a crack in the window, deepening the crisis.

André's will begins to fade as the fly's instincts take over; in a moment of desperation, he smashes the equipment, burns his notes, and leads Hélène to the factory to complete the experiment. The journey from home laboratory to industrial space marks a dramatic escalation.

At the factory, André places his head and left arm under the hydraulic press and signals Hélène to push the button. The first press descends, and André's arm is crushed free as the mechanism compacts. The act is a grim step toward final invention.

Hélène raises the press, replaces André's arm, and activates the machine a second time. The process completes the transformation, sealing André's fate and leaving the truth dangerously entangled with the couple's actions.

Back in the present, Inspector Charas and François reach the garden to see the fly, still fused with André's head and arm on a garden web. A lurking spider advances toward the trapped creature, and Charas crushes both the spider and the fly with a rock. To shield Hélène from murder charges, Charas and François decide to declare André's death a suicide.

Sometime later, Hélène, François, and Philippe resume their daily lives. Philippe and his aunt play croquet in the yard as François reflects that the search for truth is noble yet dangerous. The film closes with a quiet, ambiguous note about what really happened and what can be believed.