Claude Ridder (Claude Rich) is leaving hospital after a failed attempt at suicide, when he is asked to participate in a mysterious experiment in time travel by a private research body. They have succeeded in sending mice back unharmed for periods of one minute, but need to send a human back to confirm the subject did actually revisit the past. Claude agrees, but instead of returning promptly as the mice had done, he re-experiences many episodes from his past in a highly disjointed and fragmented manner, in interludes of seconds or minutes. Claude's observations culminate in his admission - which he later says he fabricated - that he had killed his depressed wife painlessly by gas poisoning, upon seeing her in her sleep - for the first time in her life - completely happy and without fear, and his attempted suicide upon then finding he could not live with, or without, her. The researchers wait an hour before concluding they will never get him back, and his fate is left ambiguous.