Let That Be Your last Battlefield

Star Trek Episode "Let That Be Your last battlefield" Season 3 episode 15 January 10,1969

Summary
The Enterprise becames a battlefield for two mutual hostile aliens

Plot
Stardate 5730.2 The Enterprise is on a mission to decontaminate the planet Arianias. The starship finds a stolen UFP Shuttlecraft and bring the vessel and "pilot" aboard. The newcomer is Loki a humanoid who is colored black on the left side of his body and colored white on the right side. Later the starship encounters a alien vessel that discenegrates on a collusion course-before deposting its "pilot"-a humanoid named Bele who is colored white on the left side of his body and colored black on the right side. Bele is a Police Commissioner from the Planet Cheron who has been Hunting Loki for 50,000 earth years. Bele claims Loki is a traitor and Loki claims he is a liberator. Bele tries with the force of his will to force the Enterprise to deviate to Cheron; Kirk stops him by activating the ships 30 second self destruct mecanhism. Bele relents with just seconds to spare. Loki tries to persuade the crew to support him; Bele is angered at the news the UFP will not extradite Loki to Cheron as no treaties have ever been signed with that Planet. After Arianias has been decontaminated, Bele again takes over control of the ship, using his will to destroy the navigation and self destruct mecanhisms. Both Bele and Loki fight and their personel "defense shields" nearly wreck the Enterprise with radiation; arriving at Cheron reveals the ruins of burning cities; creeping animial and vegiation and no signs of any living humanoids on the planet. Fueled by mutual insane rage Bele and Loki fight one another; Loki escapes to the trasporter room and beams down to the planet's surface; Bele follows him and also beams down in pursuit.