The disappearance of a scientific team lures the U.S.S. Enterprise to investigate near Lactra VII. TheStarship Ariel is located there, abandoned, with the Captain having transported to the planet's surface. The U.S.S. Enterprise crew beams down to discover a series of unusually juxtaposed environments. On the planet the crew meets the Lactrans, a group of 20-foot slugs with intelligent capacities far beyond their own; they capture the U.S.S. Enterprise crew and imprison them along with the three remaining Ariel crew members. Ariel's Lieutenant Randolph has become ill, but the Lactrans are unaware, as their methods of communication are highly sophisticated.

Spock can partially read the Lactran thoughts; he realizes that they are much more advanced than Vulcans and they are amused by his attempts at communication. Spock tricks a Lactran child to bring him a communicator and medical kit that are located outside a force field. Kirk contacts the ship and they are beamed up along with the child. On the starship, the child reads all the information contained in the library computer, but the child's parents are worried and almost kill Kirk in an attempt to contact him. Scotty beams down with the child, who learns that humans are not pets for Lactran amusement. The child informs the other Lactrans, who release the crew from confinement and the ships leaves with a message from the Lactrans—"humans may return when they grow up, in 20 or 30 centuries."

Cast:

William Shatner as James T. Kirk
Leonard Nimoy as Spock
DeForest Kelley as Leonard H. McCoy
James Doohan as Montgomery Scott
Nichelle Nichols as Uhura
George Takei as Hikaru Sulu

Guest Cast:

James Doohan as Lieutenant Arex
James Doohan as Lt. Cmdr. Tom Markel
Majel Barrett as Randi Bryce

Creative Staff:

Written By: David P. Harmon
Director: Hal Sutherland