The Enterprise discovers three discorporate intelligences who seek their help in gaining physical bodies... but one of them has plans of his own.
The Enterprise must destroy an enormous space amoeba before it reproduces and threatens known space.
The Enterprise travels to a planet suffering from cultural contamination from an earlier expedition--the inhabitants mimic the culture of 1920's gangland Chicago.
The Enterprise must deal with a creature from Kirk's past that feeds on human blood.
Kirk, Spock, and McCoy land on a primitive planet to negotiate a mining treaty, but soon find themselves involved with intrigue and must flee with a pregnant woman into the surrounding mountains.
Spock meets his estranged father when the Enterprise escorts a group of ambassadors to a conference on the planet Babel.
The Enterprise is taken over by a group of androids who are working for Kirk's old nemesis, Harry Mudd.
When a landing party disappears and one man is beamed up dead, Kirk, Spock, and McCoy investigate and meet a pair of aliens who seem capable of performing magic.
The Enterprise must stop an ancient doomsday weapon that is capable of destroying entire worlds... and has already totaled one Constellation-class cruiser.
Kirk attempts to assist a primitive people that are ruled over by a computer named Vaal.
The Enterprise encounters an ancient Earth probe bent on the sterilization of all life.
The Enterprise encounters an alien who claims to be the Greek god Apollo.
The Enterprise visits a colony where floral spores bring peaceful contentment.
On Eminiar VII, the Enterprise finds a civilization at war with its planetary neighbor. Unable to discern any signs of battle from orbit, Captain Kirk leads a landing party to the surface where he discovers the entire war is fought by computer. Even though the war is simulated, citizens who are listed as virtual casualties still report to termination booths to be killed for real. After the Enterprise is destroyed in an attack simulation, Kirk must fight to keep his crew from death.moreless
The Enterprise discovers a planetary population controlled by a powerful being called Landru. While investigating, Captain Kirk and his landing party are taken captive and discover that the Enterprise crew will be the next to be "absorbed" into Landru's control.moreless