While on an exploratory mission of the newly discovered planet Delta Theta III, the Enterprise crew is joined by honorary commander Ari Bn Bem, a Pandorian observer whose questionable actions while on board the Enterprise have made Captain Kirk suspicious about his motives. His suspicions are quickly proven correct when Bem sabotages the landing party, leading to their capture by the primitive reptilian beings that inhabit the planet. Kirk and Spock attempt to escape, only to discover the presence of a powerful non-corporeal alien entity that is protecting the natives in an effort to guide them towards intelligence. Written by David Gerrold, who wrote the classic original series episode "The Trouble with Tribbles," "Bem" is a terrific, ambitious and cerebral episode that -- like many of the best episodes of "The Original Series" -- finds the Enterprise crew being humbled by the presence of a very powerful race.