All eyes are on US Air Force Flight 412 as it sets off to test a new radar system. At first the mission goes well as Captain Roy Bishop (David Soul) and his crew start their hazardous journey. However when three unidentified blips appear on the Airforce Base's screen, two Marine interceptors take off to follow them, and soon disappear. It is the start of a strange chain of events, which results in an unidentified agency taking command of Flight 412. Glenn Ford gives a convincing performance as Pete Moore who, despite being given orders from the top to ignore the incident, is determined to get to the bottom of the mystery. Bradford Dillman, Guy Stockwell and Robert F. Lyons also co-star in this truly gripping movie.