The TARDIS brings the Second Doctor, John and Gillian to Arizona in 1988 where they watch an American plane crash. Soldiers arrive from a base and the Doctor tells them he watched it crash and will help discover why this has happened three times. The Doctor flies the fourth plane before it enters a death dive, but he uses his faithful rocket pack to escape, since the ejector seat doesn't work. He alter searches the desert for anything magnetic, and is captured by an enemy power using underground caves to destroy American test flights. He contacts John by walkie-talkie and asks him to send a plane filled with explosives. Tricked, the enemy causes the plane to crash and destroys the caves, with the Doctor escaping.
Like the previous story, the narration refers to the Second Doctor as Dr. Who while he is called the Doctor in the story, save for when an American general calls him "Dr. Who," which is printed on his license.