In 1943, Capt. Harold Calvert is sent to Kansas to learn to fly the newest American bomber, the B-29 Superfortress. One of the instructors is Major Tom West, a cousin of the captain. Being pressurized, the B-29 can fly higher, faster and farther than any other bomber. The top brass is closely monitoring the test flights in order to evaluate the new bomber and make recommendations. When the training and testing phase is over, the new bombers and their crews are sent to China to prepare for bombing missions against Japan. After the Americans conquer Iwo Jima and Guam, the B-29s are transferred to Guam to prepare for mass air raids against the Japanese mainland. Harold Calvert and Tom West fall for the same pretty army nurse, Lt. Helen Landers. For the next mass air raid against Tokyo, both Calvert and West are scheduled to fly together on the same bomber. But Tokyo's air defenses are formidable and many American bombers are downed by Japanese flak and Zero fighters. The bomber flown by Calvert and West is hit by AA fire and must somehow limp back home, after dropping its bomb payload. Most of its crew is badly shot-up, including Capt. Harold Calvert.