Chasing the stolen vessel Aurora, the U.S.S. Enterprise rescues the thieves just before the Aurora is destroyed. The group is led by Dr. Sevrin in a search for a mythological planet named Eden, a planet reputed to be a paradise. Sevrin's "hippie" followers take over the starship and plot a course to Eden. Upon reaching Eden, Sevrin takes his people down to the surface in a shuttlecraft and find that the planet's vegetation secretes deadly acid and the fruits are poisonous. Madly refusing to believe, Sevrin bites a piece of fruit and dies.

James Doohan (Lt. Cmdr. Montgomery Scott)
Skip Homeier (Dr. Thomas Sevrin)
Charles Napier (Adam)
Mary Linda Rapelye (Irina Galliulin)
Walter Koenig (Ensign Pavel Chekov)
George Takei (Lt. Hikaru Sulu)
Majel Barrett (Nurse Christine Chapel)
Victor Brandt (Tongo Rad)
Elizabeth Rogers (Lt. Palmer)
Deborah Downey (Mavig)
Phyllis Douglas (Girl Hippie)