John is first seen when Thomas wakes up in the Box and is brought to the Maze. He is later seen working around the Glade. When Thomas freaks out after Gally pushes him away from the maze doors, John, along with Mike, Jack and three other gladers run over to them. He is later seen partying with the other Gladers. In a deleted scene, he is seen cooking and serving Gladers lunch along with Frypan and Carl. When Minho is carrying Alby, he, along with the other Gladers, yell at him to hurry. He then witnesses Thomas go into the Maze. When Thomas, Minho, and Alby come back from the Maze, John is seen running up to them along with Carl to see what's going on. He later witnesses Teresa wake up. During the Griever attack, he hides and survives. He is later seen in the offering. He is one of the many Gladers to stay behind with Gally when Thomas leaves. John, along with Carl, are last seen checking on an unconscious Alec on one of the monitors Newt is looking at. He did not appear in the books.
The name John is seen on the memorial rock at the end of the movie, confirming his fate.