SHADO officially goes into operation and encounters its first UFO. An alien pilot is captured and discovered to have transplanted human organs within him.

When civilian test pilot Paul Foster inadvertently witnesses a SHADO operation, he is given a choice: join SHADO or die.

Straker faces a terrible decision: attend to an alien defector or deliver life-saving medicine to his critically injured son.

Communications problems at Moonbase are traced to a non-SHADO mining operation.

After Lunar Module 32 is mysteriously destroyed, Straker campaigns to have space junk removed from Earth's orbit.

A flashback episode focusing on SHADO's formation and how it caused the failure of Straker's marriage.