Thomas and Minho see a Griever roll right off the edge of the Ciff one day while running, so they decide to investigate. Minho explains that Gladers have tried throwing rocks off the edge before, but they just fall. However, when they throw a rock roughly where the Griever disappeared, they see the rock disappears instead of falling. They investigate further, throwing rocks at every space moving left to right in rows that move further away from the edge. They work out there is a hole where the rocks disappear instead of falling. They realise they have discovered the Grievers' lair.
At the end of The Maze Runner, Teresa and Thomas realise that it is the exit. They know that the Maze is a code, making a letter each day to form a code they must punch in to open the exit. However, as the Gladers run to the Cliff to leave the Maze once and for all, they find a lot of Grievers on the final path. The Gladers fight the Grievers while Thomas, Teresa and Chuck run past, jump down the hole and punch in the code to deactivate the Grievers and open the exit. They suceed, although a few Gladers die fighting.