The lightship Altares leaves Space Station Delta on the first stage of a mission of scientific discovery beyond the solar system, a journey to Alpha Centauri, four light years from Earth.

Two teens, John and Julie, find themselves ⅓ normal size due to the work of the unseen "investigator", an alien being only seen as a green star in the teens' cave base.

After 15 years with the New York Police Department, Lieutenant Chuck Brogan has transferred to the Space Police, becoming the commanding officer of Precinct 44 East.