Man oh man, the ending. The epilogue of the story is a memorandum from Ava Paige, the Chancellor of WICKED, to all of her associates discussing how amazingly the test subjects succeeded in their little experiment. She feels a little bad about, oh, ya know, the dead kids and all, but they really exceeded her expectations.
The "rescue," it turns out, is just yet another variable in their scheme, so she has a little guilt about seeing them all relieved and feeling safe, but you do what you have to do in this day and age. Yuck. Then, Dashner drops this bomb on us: they were only Group A. As in, Group B also did well in the experiments. There are even more kids who have been put through the wringer in order to "serve and preserve humanity, no matter the cost" (E.5).
Apparently, the kids are going to be allowed one night of peace and quiet, and tomorrow the shenanigans will begin anew.
What this does is jump start us into the sequel. Try as you might, no matter how many times you turn the page there won't be any new information until you buy The Scorch Trials. Do you want to know what happens to the kids tomorrow? Buy the next book. Want to meet Group B? Better buy the next book. Want to know when the dang experiments end? Tough, you've gotta buy the next book.