Beware of the Grievers. Yahoo debuted a longer trailer for YA novel-turned-movie “The Maze Runner,” and the new footage shows more of the Glade made infamous in James Dashner’s trilogy.

“The Maze Runner” follows Thomas (“Teen Wolf” star Dylan O’Brien), a teenage boy sent to an exiled community of kids who live in the Glade, a giant green space surrounded by the mysterious maze. The kids have no memories of life before the Glade and they live and die by Grievers, horrifying monsters who inhabit the maze. (The new trailer shows a few glimpses of the nasty slug-like beings.) Also starring Kaya Scodelario, Will Poulter, Thomas Sangster and Aml Ameen, “The Maze Runner” hits theaters Sept. 19.