He regains consciousness when he hears Chuck speaking to him, asking him not to die.
He remembers all the things that were shown to him: the Maze can't be solved, and the only way out was something horrifying, almost impossible.
Chuck is super-psyched that Thomas is awake, and he updates him on what he's missed during the three days that he was going through the Changing.
Grievers came and took one boy each night true to pattern—Zart was one of them.
Thomas tells him that they need to have a Gathering as soon as possible.
He reaches out telepathically to Teresa and she scolds him for how stupid he was to get stung on purpose.
He remembers that they've done some bad things together, but won't reveal everything until the Gathering because he's too tired to explain twice. All he will say is that the Creators meant for them to escape, and the whole experience has all just been a test. The Creators kept throwing variables at them to weed out the best candidates and try to make them quit. Escaping is the final test.