"Patterns of Force" is a second season episode of the original science-fiction television series, Star Trek, and was first broadcast on February 16, 1968. It is episode No. 50, production No. 52, written by John Meredyth Lucas, and directed by Vincent McEveety. This episode was banned on German television from 1968 until 1995 due to the depiction of Nazi uniforms and presence of several different nazi insignia.

In this episode, the crew of the Enterprise tracks down a Federation observer on a planet dominated by a "Naziesque" regime.

The starship Enterprise arrives at the planet Ekos in the M43 Alpha system, to investigate the disappearance of a Federation cultural observer named John Gill, who was one of Captain Kirk's history professors at Starfleet Academy. As soon as the Enterprise enters orbit around Ekos, it is attacked by a rocket armed with a thermonuclear warhead, technology that is no match for the starship but too advanced to be from either primitive, warlike Ekos or their neighboring planet, peaceful, more progressive Zeon. However, the latter has achieved intrasystem spaceflight and developed an interest in assisting their neighbor, resulting in a significant Zeonian population on Ekos.

Kirk suspects Gill may be responsible for the introduction of more advanced technology somewhere in the system—which would mean that he has contaminated Ekosian culture and hence violated the Prime Directive. Kirk and Executive Officer/Science Officer Spock decide to beam down to the planet to investigate. Before they transport to the surface, Kirk has Chief Medical Officer Dr. McCoy insert subcutaneous emergency transponders, a type of homing device, into the forearms of each in the event they cannot use their communicators.

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