A teenager wakes up inside an underground elevator with no memory of his identity. A group of male youths greet him in a large grassy area called the “Glade” enclosed by tall, stone walls. The boys (“Gladers”) have formed a rudimentary society with each assuming specialized tasks. Their leader, Alby, says that every boy eventually recalls his name but not his past. The boy learns that a vast Maze surrounding them may be the only way out. During the day, designated Runners search the Maze for an escape route, returning before nightfall when the entrance closes.
While in a competition with another boy named Gally, the boy suddenly remembers his name: Thomas. The next day, he is attacked by Ben, a Runner delirious from being stung by a Griever – deadly techno-organic creatures that roam the Maze at night. Ben is forced into the Maze and left to die, as there is no cure for his injury. Alby and Minho, the lead Runner, later retrace Ben’s steps inside the Maze. Minho reappears at dusk dragging Alby, who is stung, but they are unable to reach the closing entrance in time. Thomas runs into the Maze to help, leaving all three trapped. Thomas lures a Griever into a closing passageway, causing it to be crushed. The trio manages to survive the night, returning the next morning.
The first-ever girl arrives in the elevator. She recognizes Thomas, though he cannot remember her. Thomas, Minho, and others enter the Maze, locate the Griever corpse, and remove a beeping mechanical device from inside it. Gally claims Thomas has jeopardized the fragile peace between the youths and the Grievers and wants him punished, but Newt, the group’s second-in-command, instead designates Thomas as a Runner. Minho shows Thomas a hand-constructed model of the Maze based on previous exploration. The Maze’s numbered sections open and close in a regular sequence. Thomas realizes that the device corresponds to a section within the Maze.
Teresa has two syringes filled with an unknown substance. One is used on Alby, and he recovers from the Griever sting. Minho and Thomas venture back into the Maze with the device and discover a possible exit. That night, the Maze entrance does not close while others open, letting Grievers pour in. A massacre ensues as the Gladers struggle to fight back or hide. Alby, Zart, and several others are killed.