Frank Wead wrote this drama about flight surgeons and test pilots trying to solve the problems of high-altitude flying.
The film was supported by the U. S. Navy and dedicated to its flight surgeons. The squadron of Commander Joe Blake (Fred MacMurray) takes off from an aircraft carrier. In Hawaii a diving pilot passes out and crashes. Lt. Doctor Doug Lee (Errol Flynn) persuades Dr. Martin to operate right away. Lee tells Joe and Lt. Tim Griffin (Regis Toomey) that the pilot died. Lee tells Linda Fisher (Alexis Smith) she is too good for him. Lee asks Joe and Tim about the blackouts.
In San Diego Joe trains Navy pilots. Lee reports as a flight surgeon to researcher Dr. Lance Rogers (Ralph Bellamy). Joe assigns Tim to train Lee as a pilot. Lee flies with Joe upside down. Lee drives his car into the car of John Thomas Anthony (Craig Stevens), and they fight. Lee asks Joe to stop riding him and in class talks back to Dr. Rogers. Art Lyons (Robert Armstrong) tells Lee that Dr. Rogers hurt his heart experimenting and can't fly anymore. Lee volunteers to help Dr. Rogers in the lab, and Dr. Rogers makes Lee his assistant. Joe makes a date with Linda, who is glad to see Lee. Joe tests for blackout with Lee. Lucky (Allen Jenkins) hides from his wife (Dennie Moore).
Lee suggests a belt to keep blood above the heart and tests it himself in Joe's plane; it works. Lee and Dr. Rogers tell Tim his heart is worn out. Tim says he'll quit to fly elsewhere. Test pilots collapse after landing. Tim in the Royal Air Force lands. Joe buys him a hamburger, and Tim takes off for Seattle. Joe hears that Tim was killed landing. Joe volunteers to test for Lee and Dr. Rogers. In the lab Anthony goes without an oxygen mask and passes out. Lee gives him one, and he recovers. Joe suggests a pressure suit, and Lee works on it. Dr. Rogers tells Lee that Joe is getting fatigue. Lee sends Lucky, who hides from his wife while his friend makes a date with her. Lucky has to stay in isolation for 21 days. Lee sees Joe dismiss Anthony and gets him another chance. Out dancing, Lee and Joe ignore Linda and another woman to discuss a valve.
In a plane at high altitude Joe and Lee have troubles with ice and low pressure. Joe faints, and the plane tailspins. Lee brings it out. Lyons' pressure cabin did not work. Lee has the suit made and tested in the lab on Joe. Dr. Rogers learns Joe has chronic fatigue, and Joe tells him. Joe puts on the suit and takes off. Lee and Dr. Rogers talk to Joe by radio. Joe can't get oxygen and writes a note to heat the line. Joe loses control and crashes. In the final scene Dr. Rogers and Lee are honored, and Joe is remembered. Anthony tells Lee he volunteers, and Lee flies with them in his suit.
Only months before the Pearl Harbor attack, this film
prepared pilots for the war, referred to as the imminent "main
event," by showing the experiments that would allow them
to gain the high position of being above their enemies.