This time out of the maze the kids are taken to a base where other kids from the maze are. We find out who put them in the maze, why most people stay in the maze, and what is just beyond the maze. I don't want to give away spoilers, but you literally cannot trust anyone or get attached to anyone. Any character may betray you and/or die.
This is one of my fave tween movie series ever. Cannot wait till they're all done so I can own the series. 5 out of 5 stars easily.