Feeling drugged, Thomas wakes up in an elevator car with no memory except his name. He finds he is part of a community of about 50 teen boys called Gladers, and all share the same pattern of memory loss. Their leader’s name is Alby. In an artificial environment built as an experiment by unknown, unseen scientists called Creators, they live in the Glade, and their lives revolve around trying to solve the Maze, a gray stone structure with walls hundreds of feet high. Entrances to the maze automatically close at the same time every night, which protect the Glade from Grievers large part-animal, part-mechanical monsters that bite, sting and sometimes kill.
Occasionally a Griever stings one of the boys. If the victim returns to the Glade in time, he can be injected with a serum that saves his life; but it causes a strange, painful process. The boys call it the Changing when part of the victim’s memory returns but those who have lived through the Changing all agree that the real world is one they don’t want to return to. The few boys who have undergone the Changing say they have seen Thomas in it, and they are convinced that he is bad or perhaps a spy.
Chuck, the youngest in the compound, is assigned to Thomas to help him acclimate. He is the only one to offer Thomas friendship. Thomas spends his first couple of days learning the ropes and various work positions, such as Baggers and sloppers Runners are the boys who daily run through the Maze, and when they return just before night, they map the section they ran since each night the walls move, reconfiguring the Maze. The group has been working for two years to figure a way out of the Maze. Thomas notices that parts of his new life somehow seem familiar, with fleeting impressions of memories just out of reach. He feels driven to be a Runner.
Every month, a new boy arrives in the elevator. But on Thomas’ second day, the elevator brings a teen girl. Nearly comatose, Teresa has little memory remaining, and it is quickly fading. She remembers that she is being sent as a trigger to begin the end of life in the Glade. Later, when Teresa emerges from her coma, Thomas discovers that Teresa can communicate telepathically with him, and they deduce that they must have known each other before their arrival.
One evening, as time draws near for the walls to close between the Maze and the Glade, two of the runners have not returned. As the walls nearly finish closing, Thomas sees the two runners but realizes they won’t make it. Breaking the No. 1 rule to never leave the Glade at night, he squeezes through the walls at the last second, and he is terrified to find himself in the dark silence of the Maze. Miraculously, Thomas and the two runners survive their night in the Maze by outwitting several Grievers. Because no one has ever survived before, Thomas becomes a hero and then is promoted to Runner.
The end to life in the Glade is triggered when they all awaken one day to the absence of what they thought was a sun, and the fact that they exist in a fabricated place seems more apparent. Supplies stop arriving, and the walls stop closing, compromising their protection from the Grievers. The community is thrown into a panic. They learn that the Grievers plan to kill one child a day until they’re all dead.
Thomas finally decides that the best way to solve the Maze is for him to get stung and endure the Changing in order to retrieve some of his lost memory. His plan succeeds when the Grievers invade the Glade. Thomas goes through the Changing and learns from it that the boys in the Glade have above-average intelligence and are part of an experiment to test for survival of the fittest. The Creators took them from their homes when they were young, following a catastrophic event called the Flare. Some of them have had their brains altered. The ones who survive are to be used for an unidentified but important purpose. He also learns that he and Teresa were part of the group that planned the Maze.
Thomas comes up with a dangerous plan to escape. The plan works, but half of the group dies in the process. Their escape from the Maze ends in a confrontation with two of the Creators, who mind-control another boy who had disappeared earlier from the Glade. The boy throws a dagger aimed at Thomas, but Chuck moves in front of it and is killed. Suddenly an apparent rescue group arrives on the scene with weapons, shooting and killing one of the two Creators. Then they flee, along with the kids. They board a bus and drive for two hours to a new location. During the ride, a woman tells Thomas and Teresa about the outside world’s catastrophe: A massive solar flare scorched the earth, leaving millions of people dead and diseased. Much of the earth has become a wasteland. She tells them that this group they are with now is against the Creators and their testing of children. Book one ends with a memo from the World in Catastrophe: Kill End Department (WICKED), known to the kids as the Creators. It says that what the adolescents just lived through was only the first stage of their trial.