| Director | Edward Dmytryk |
|---|---|
| Box office | $3.3 million |
During a power outage in the Unidyne building, a New York City skyscraper, David Stillwell leaves his colleague Josephson on the 27th floor and begins his descent down the stairs, aided by a penlight. He encounters an attractive young woman who wants help navigating the darkness. Recognizing his voice, she welcomes him back and wonders why the major shut off the power. Stillwell protests that he has not been away, does not know a major, and has never seen her before. They are about to exit to the street when he introduces himself, confirming she was right. Confused and angry, she runs down the basement stairs. He calls after her and looks down to the sub-basement, but she has disappeared.
Outside, Stillwell sees a crowd gathered around the body of peace activist Charles Calvin, who fell from the window of his 27th-floor office. When the lights come on, Stillwell looks for the woman inside and finds there is no sub-basement. A menacing man, Willard, is working in the basement and orders Stillwell to leave.
Threatened at his apartment by the major's henchman Lester, Stillwell does not understand what he wants. Reporting the incident at the police station, Stillwell becomes distressed by basic personal questions and storms out. Realizing there are gaps in his memory, he consults a psychiatrist, Dr. Broden, who is dismissive of his claim of amnesia.
Stillwell hires private detective Ted Caselle, who believes him only after spotting Willard following them. At the Unidyne building, they discover that Stillwell has no office, and while checking the basement, they are shot at by Willard but escape.
The woman from the stairwell, Shela, re-appears and tells a baffled Stillwell that the major wants something from him. According to Shela, she and Stillwell once had a relationship, and they spend the night together. In the morning she is gone and two henchmen try to take Stillwell, but he escapes after using Lester as a shield against Willard's gunfire. Caselle is murdered and Stillwell, after a chase through Central Park, is saved when a car runs over the henchman Bo.
Stillwell has flashbacks and believes his amnesia is just two days old. Dr. Broden, now more sympathetic, suggests that false memories have displaced recent traumatic ones. Stillwell is a physiochemist who worked for Unidyne until Charles Calvin convinced him to conduct research at a California laboratory. After discovering a way to neutralize nuclear radiation, he returned to New York for a meeting with Calvin at the Unidyne building and learned of the illegal connection between the peace advocate's foundation and Unidyne's president, former army major Crawford Gilcuddy, who would use Stillwell's discovery for warfare. The major had the power shut off in an attempt to stop Stillwell from leaving the building. To prevent any misuse of his discovery, Stillwell burned the formula, at which Calvin made a desperate lunge and tripped out of the window to his death. The trauma of witnessing this triggered Stillwell's amnesia.
In a confrontation that includes Josephson, Willard and Shela, the major tries to force Stillwell to recreate the formula. Shela shoots Willard as he holds a gun to Stillwell's head. Turning against the major, Josephson calls the police. Stillwell and Shela embrace.