An introductory WWII newsreel sets the stage. D-Day is fast approaching, but the exact date and designated invasion beaches are closely-held secrets. The British Isles are bulging with troops, ships and equipment.The story begins in London on May 31, 1944. An American army major, Jefferson Pike (James Garner), enters Allied Forces HQ to discuss the ongoing invasion preparations. The top brass aren't convinced that Allied deception efforts have fooled the Germans. While poring over a wall map of German troop dispositions in France, Pike inadvertently slides his finger along the edge of the map, incurring a nasty paper cut.To hedge their bets, the High Command sends Pike to Lisbon to meet with a German double agent and see what he knows. Pike expresses concerns that if captured and tortured, he might reveal exact invasion details. His superiors feel that the risk is justified. As Pike flies out of London in civilian garb, a German spy sees him boarding the plane and reports it to her handlers. Another German spy enters his vacant hotel room and gathers personal items, including photos, letters and hair samples from his brush.In Lisbon, Pike goes to a nightclub to meet his contact but quickly realizes that his drink has been drugged shortly before he passes out. He is soon in German hands, placed in a coffin as a deceased German embassy clerk, and flown to Germany. An American-born German army major, Walter Gerber (Rod Taylor), is a military psychiatrist in charge of an elaborate deception scheme designed to coax the invasion secrets from Major Pike. An entire "American" military convalescent center has been set up deep in a German forest to fool Pike. Major Gerber is given 36 hours to extract the invasion plans from Pike. After that, Pike will be handed over to the SS to gain the information through their usual means. Gerber also understands that the consequences of failure will be catastrophic for his own future.When a groggy, disoriented Pike finally awakens, he is relieved to find himself in Allied hands. Looking in a mirror for the first time, he is shocked to find his dark hair streaked with gray, his skin aged, and his vision blurry. His every move is observed through a two-way mirror. Piece by piece, Pike is sold the idea that it is now May 1950, the war is long over, and he is convalescing at an American military hospital in occupied Germany. Both Major Gerber and pretty nurse Anna Hedler (Eva Marie Saint) are leading actors in the ruse. Pike's room contains familiar photos and Anna is able to provide accurate details about his parents. Rigorous measures are taken to ensure that Pike is surrounded by dozens of role players who are fluent in American speech dialects and customs. No one is allowed to speak German, even out of Pike's hearing. Pike is told that he is suffering from severe amnesia, a side effect from the severe "beating" he supposedly absorbed after the Lisbon incident six years earlier. According to the cover story, Pike was found wandering alone in Lisbon and sent back to the US to recuperate, but continual regressions over the years dictated that he be sent to Major Gerber in Germany for experimental psychological therapy.His nurse tells him that she and Pike have been married for two months, but due to another regression he doesn't remember her. In an unguarded moment with Anna, Pike asks about the war's closing months and mentions something about the invasion sites having been in Normandy. She tries to conceal her shock and reports the sensational disclosure to Major Gerber, who then manages to skillfully extract the most important invasion details from the trusting Pike. The race is on. The date is now June 2.After the session with Gerber, Pike is absent-mindedly rubbing his fingers together when he suddenly irritates the painful paper cut incurred in London two days earlier. Gradually recalling the injury, confusion registers on his face. With his suspicions aroused, Pike takes steps to confirm his worst fears and then violently confronts Anna, who admits to the elaborate plot. She explains that she went along with the ruse in order to buy her way out of a concentration camp. Out of hatred for her captors, she agrees to help Pike. He tells her to run out of his room screaming that he has escaped and that he has known about the plot from the outset. Pike slips out the back way, knowing that he will be caught. Now the Germans must determine whether Pike was telling the truth about Normandy or trying to deceive them.A disappointed Major Gerber asks how and when Pike figured out the scheme and Pike tells him about the paper cut. Gerber explains that Pike was carefully examined for injuries when he arrived, but the cut was obviously concealed in a skin crease. Gerber still thinks Normandy was a truthful answer, but he knows no one will believe him. The SS indeed discounts Pike's accurate story and allows the bulk of the German forces to remain idled near Calais. Gerber explains regretfully that Pike will now be handed over to the tender mercies of the SS.Hating the SS and realizing that he will probably be executed for his costly failure, Major Gerber settles on a daring plan to have his pioneering research on psychological combat trauma live on. He gives his research papers to Pike and Anna, advises them how to get across the border, and helps them escape from their locked room.The race for freedom is now on, with a zealous SS officer trying to capture the pair before they can escape over the Swiss border., Question: How does Pike figure out its a scheme?
Output: Answer: paper cut