Summary...

A teenage boy wakes up in an elevator with no memory of his past other than the fact that his name is Thomas. When the elevator doors open, he is pulled into The Glade by a bunch of teenage boys who also have no memories besides what they should be called.

Thomas gradually discovers that the Glade is run by two boys, Alby and Newt, who maintain order by enforcing strict rules. He also learns that every month a new person is sent up into the glade and that every week or so supplies are sent up in the box which delivered Thomas. He is the told about Beetle Blades, small metal creatures that record everything the Gladers do. The boys are divided into different groups and have different jobs. Outside the Glade is the Maze, a labyrinth of high ivy-covered walls that houses strange, lethal creatures known as Grievers. A group of the boys called Runners are trying to stay alive as well as "solving" the Maze by running through it as fast as they can while tracking movements of the walls and trying to find an exit. Every day at sundown, the entrances to the maze shut, and the Grievers come out and start patrolling the Maze while the corridors change. The leader of the runners, Minho, befriends Thomas.

After Thomas's arrival, the first and only girl is delivered through the elevator into the Glade, and subsequently collapses into a coma after stating "Everything is about to change to change”. A note is found in her hand saying ‘She’s the last one. EVER.’. To make matters worse, her arrival triggers everything in the Glade to change: the sun disappears, the deliveries of supplies stop coming, and the doors stay open at night which allows the Grievers to enter the Glade to hunt the children, but, for some reason however, they only abduct one boy every night.

Thomas proposes that the walls of the Maze aren't random, but that their movements are actually a code, leading to the discovery that the maze is spelling out words. Thomas also discovers that the Cliff that they all thought was just a cliff turns out to be where the Grievers are coming from, a 2 cm wide whole invisible to sight right of the cliff. If they can come and go over the edge of a cliff, then maybe so can the boys.

The girl, Teresa, wakes up and tells Thomas that they knew each other before they were put in the Glade, and reveals that they can communicate telepathically.

In an act of desperation to get his memory back, Thomas gets himself stung by a Griever and discovers the Griever Hole is indeed an exit. Furthermore, the code that the Maze has been spelling out is their ticket to escape.

A large group of the teenagers decide to make a run for it, fully knowing that it could be suicidal trying to take on the Grievers but figuring that nothing could be worse than being stuck in the Glade. They make it into the Griever Hole where they find a computer system and enter the code from the maze. The Grievers shut down and an exit opens up through which they escape, only to find out that what they've been doing is an experiment being conducted by a group called WICKED (World In Catastrophe, Killzone Experiment Department), who may or may not be evil. The boys and Teresa then get "rescued" by rebels and are brought to a safe haven while being told about "the Flare"—an apocalyptic neural disease that has killed most of the world's population.

In the epilogue it is revealed that the "rebel group" may just be another variable in the experiment, and they weren't the only group being evaluated.