Issue Number 1
Spock and Dr. McCoy are gathering supplies in sick bay for the landing party. Suddenly, the laboratory guinea pigs begin squeaking frantically. The two go and look at the animals just in time to see them mutate into a form of plant! Before they can react, all of the other lab animals have transformed into "giant, hostile trees" which go on a rampage and try to destroy them. Spock calls for security. The guards arrive, and Spock orders them to fire their phasers at the central "pollen areas" of the plants. The plants are destroyed just in time before they crush McCoy and Spock with their tentacles. "We'd better report this to the Captain at once!" says the Doctor (really... you think?!) "no telling where or when those plant creatures will pop up again!"
Kirk calls an emergency conference to discuss the creatures. Spock suggests that they may be related to tests that were performed in space weeks ago on the laboratory animals, and that the animals may have picked up "alien spores." Kirk orders Spock to continue research on his theory, while he beams down to the surface along with Dr. McCoy, Yeoman Janice Rand, and several security guards. He tells Spock that he will make an "hourly t.v.-radio report" back to the ship.
The landing party arrives on the surface of the planet K-G (newly named in honor of Scotty's comment on the bridge), and begins a search. Crewman Hunt passes through a patch of the mysterious mist. He begins sprouting branches and turning into a plant, just like the animals on the ship had! At that moment, the crew members are pulled backwards toward a huge cannibal plant, which is trying to suck them in. Just before they are devoured, a giant tree attacks the cannibal plant and destroys it. After the battle, the giant tree collapses to the ground dead. The landing party discovers crewman Hunt's identification bracelet around one of the branches, and realize that Hunt had become the giant tree! He had died trying to save the landing party. The crew buries the remains of the tree in a shallow grave.
Kirk calls the ship and tells Spock what has happened. He decides to keep the landing party on the surface of the planet in order to find out what is causing the mysterious plant attacks. The party walks through the forest and comes upon a "community of vegetation", with plant creatures, houses, and buildings just like on Earth! The Captain realizes that it is an intelligent society, and leads the party toward the village for a closer look. As they approach, the party is suddenly attacked by trees on all sides. The crew members use their phasers to blast a path through the living trees and escape. The party sees a natural cave, and uses it for shelter. As they rest, a huge crawling vine attacks them! The creature wraps Yeoman Rand up in a tentacle, and takes her from the cave.
The remaining members of the landing party chase the giant plant. It takes Yeoman Rand to a large "cattle pen" made of thorns, and deposits her inside, where other animals are grazing. The landing party tries to use their phasers on the thorny wall of plants, but the thorns regenerate as fast as they are destroyed. Kirk guesses that the large plants use the animals for food, and since Janice is with them - she is in danger of being eaten!
Kirk calls the Enterprise and orders Spock to fire a pinpoint "laser beam" at the wall of the pen. The blast destroys the pen, and kills a large plant creature that is about to devour Yeoman Rand. The landing party rescues her, and Kirk tells Spock to bring them back up to the ship. They are beamed up just in time, before more deadly plant spores "pollinate" them.
When they arrive on the Enterprise, Spock tells Kirk that if the spores from the planet continue drifting through space, other planets may be in danger. "We must orbit that hideous little globe until all foliage upon it is decimated by our laser beams!" Spock says. "I have set a course for the mission already!" The Enterprise moves slowly over the surface of the planet - using its weaponry to destroy all life, before it can continue its tour of research through the vast reaches of the universe.