At a NATO airfield somewhere in England, parachute designer Jim Radford anxiously watches the testing of his new-style parachute with General Armstrong and his aide Lt. Bailes as observers. The plane comes into sight, and on a signal, three paramen leap out. For some seconds they fall through the air floating earthwards. Suddenly, an eerie sound fills the air. There is something wrong, horribly wrong. But this is only the prelude to some further weird events.