Michael Barrier

Encountering an uncharted planet in an empty region of space, Kirk and his crew are entertained by Trelane, a playful being who lacks the self control to wield his great psionic powers with discipline. When he threatens the whole ship, Kirk himself faces down Trelane's tantrums until relief surprisingly arrives.

Aliens on a mission of conquest hold the crew captive.

The Enterprise visits a colony where flower spores provide the settlers with peaceful contentment — and Spock finds he can experience love. The spores also offer protection from fatal stellar radiation, but Kirk's crew finds they also have a more sinister effect.

After white men slay his father, half-breed Quint Asper joins the Comanche tribe of his Indian mother so he can avenge the killing.

Chester finds himself the unwilling guardian and nurse of a runaway Indian who has been befriended by a young white girl.

A pre-Gilligan's Island Alan Hale Jr. appears in this episode as Omar Keck, an eccentric millionaire who has financed an experimental missile which he intends to send to Mars. Not surprisingly, Uncle Martin (Ray Walston) is the first to volunteer to pilot the vessel into space. In anticipation of his flight, Martin allows Tim (Bill Bixby) to publicly reveal his true Martian identity--but only after he has safely begun his homeward journey. Needless to say, things don't go quite as expected!