So there's this kid who wakes up in an elevator with no memory of his past other than the fact that is Thomas. When it the elevator doors open, he is pulled into a huge glade by a bunch of teenage boys who also have no memories besides what they should be called. They all share a strange vocabulary, a fondness for capitalizing words to make them special, and the same mysterious fate.
Thomas gradually discovers that the Glade is run by two boys, Alby and Newt, who maintain order by enforcing strict rules and keeping all of the boys busy harvesting food. This is important because outside the Glade is the Maze, a terrifying labyrinth of high walls covered in ivy that houses strange, lethal creatures known as Grievers. So the boys are stuck 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.