The Thief (1952)

Ray Milland plays Dr. Allan Fields, a nuclear physicist who works for the Atomic Energy Commission in Washington, D.C.. But Fields is also a spy working for an unnamed foreign power. Through a series of elaborate devices and plans, Fields takes secret photos of his top-secret work and passes the secrets, through a vast network chain in New York City, to an apparently enemy country. The latest canister of microfilm the doctor sends out is picked up by authorities after the courier is killed in a traffic accident in New York's Central Park with the documents in his possession.

Fields comes under suspicion by the FBI. Now scared and paranoid, he stays overnight in a cheap hotel, waiting for a call on the hall phone to give him instructions on his next move. After he has finally been contacted, he is tailed by an FBI agent to the Empire State Building. While at the observatory tower, Fields meets his contact. The alert FBI agent spots this and pursues Fields who climbs even higher; at one point Fields fights off the agent causing him to plummet to his death. He escapes from the building with papers in hand that will get him out of the country, but he becomes shaken by the sight of the dead agent on the sidewalk. The doctor finally breaks down back in his hotel room after realizing what he has done, and gives himself up to the FBI the next day.