When a Lunar Module is attacked by a UFO, Straker makes a split-second decision that endangers the astronauts, but ultimately saves them. Later, he is surprised to find his authority being questioned by his most loyal officer, Colonel Paul Foster, who spearheads a campaign against him. Then an attempt is made on Straker's life...

Straker gets approval from above to build a probe with a camera that will track a UFO back to its home planet. Inexplicably, the Earth technology is capable of following a UFO travelling 8 or 9 times the speed of light and follows it home. The episode ends with a SHADO guy trying to convince Straker that they were wasting their time, even though they picked up some great pictures of the planet.

Foster, whose radio is knocked out and his oxygen line cut, is presumed lost (but they did a crummy job, not even trying to find his body) during a confrontation with a UFO on the moon's surface. Foster is found by an alien, and together, they cross the lunar landscape, developing a friendship when the alien must try to do make-shift repairs on Foster's suit to keep him alive. At the end, a Moonmobile crew finds Foster and misunderstands his intent when he points them to the alien nearby.

Two of the SHADO people, dining at a fancy restaurant, begin to recall this event after one of them sees a diner who was part of Dalotek. A private company installed a facility on the moon which discovered an alien device that disrupted Communications between Moonbase and SHADO on Earth.

Freeman takes over temporarily while Straker deals with a woman apparently determined to investigate what SHADO is all about.