USAF Major Lincoln Bond is captured, tortured and released from a POW camp in Korea. After the war he returns to the US where he is re-assigned as a test pilot at the Flight Test Center at Edwards Air Force Base. The Air Force is testing the new experimental aircraft Gilbert XF-120 fighter. The acceptance of the new aircraft by the Air Force is dependent on successful tests designed to prove the aircraft's reliability and safety. However, when Major Bond flies the prototype he encounters a problem that points out a dangerous structural flaw. This could threaten the aircraft's acceptance by the Air Force and derail the whole project. Major Bond's commanding officer and some of his colleagues start to suspect that Major Bond is imagining things because of his mental condition dating back to his imprisonment and torture in the Korean POW camp.
Toward the Unknown
At the dawn of supersonic flight in the 1950s a group of Edwards Air Force Base experimental aircraft test pilots push themselves to the limit.