Although the dark clouds of war had enveloped the European continent in 1917, the small towns in the United States were quiet as usual. The girl next door, Maryin love with a warm and cheerful Jack, he has no sleep, instead of ladylike Servierunrequited love, but Schwing Ya'ai’s is actually Davidyounger brother of the family . Jack and David signed up to join the army by appointment and were assigned to receive pilot training in the same barracks. When they were practicing boxing, the two of them fought in a fake game. David was knocked to the ground, but he never gave in, and he still had to get up and fight again. Jack admired his spirit, and the two turned their enemies into friends. Jack and David had the opportunity to go to Europe to fly a plane and each made their own combat exploits. In Paris, they used wine and beauties to relieve the pressure of war. Mary took part in the rescue work and came to Paris. She met a drunk Jack. Mary helped him to the room, but was misunderstood by the officer that they had an affair. Mary was dismissed as a soldier and returned home with regret.
Before the flight, Jack saw Mary's news in the newspaper and reacted fiercely. He and David had a small misunderstanding because of Shivia's photos. In combat, David was shot and the plane crashed behind enemy lines, but he survived. But Jack thought that David was killed in battle, filled with righteous indignation, and risked fighting with enemy planes to avenge his friends. Unexpectedly, when he returned home, David stole a German plane and drove over. Jack thought that the enemy was coming, so he shot David to death, and he regretted it when he knew the truth.
After the war, Jack returned to the barracks and saw Shivia's photo and her letter of love to David, which made him feel more guilty. He returned to his hometown and went to ask David's parents for crimes. David's parents didn't blame Jack, they only blamed the war. Afterwards, Jack and Mary met again. He confessed to her that he had been with an unknown woman in Paris. Mary knew that that person was herself, and smiled to indicate that everything was over. After all the twists and turns, Jack and Mary finally found love
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