The 18th episode of the animated Star Trek series on NBC. The episode is written by The Trouble With Tribbles writer David Gerrold. 
Stardate 7403.6: Commander Ari Ben Bem, a native of an advanced planet which the Federation hopes will soon join its ranks, accompanies the Enterprise crew for several months, though he has spent virtually all of that time in seclusion. However, when the opportunity to beam down to the newly-charted planet Delta Theta III presents itself, Bem all but takes charge of the landing party (much to Kirk’s annoyance). Delta Theta III turns out to be inhabited, and Bem quickly puts the Enterprise officers in harm’s way. When Kirk and Spock try to escape and take Bem back with them, they discover that they’re not the only intelligent beings who are interfering the the planet’s life forms.
written by David Gerrold
directed by Hal Sutherland
music by Yvette Blais & Jeff MichaelCast: William Shatner (Captain Kirk), Leonard Nimoy (Mr. Spock), DeForest Kelley (Dr. McCoy), James Doohan (Mr. Scott), George Takei (Lt. Sulu), Nichelle Nichols (Lt. Uhura / Alien), James Doohan (Scotty / Bem), Majel Barrett (Nurse Chapel)
LogBook entry by Earl Green