Atherton #3: The Dark Planet (No. 3) by Patrick Carman

the two men were in pain.
    When the door was shut and the room was dark again, Aggie
    whispered as quietly as she could.
    "It wasn't that bad. Socket hardly knows how to use that thing."
    Teagan knew Aggie was only trying to put on a brave face, but
    she didn't say anything. She just reached over and held her
    friend's hand. A few minutes later, when Aggie thought Teagan
    was asleep, she began to cry quietly.
    "Move over," said Teagan. She crept into Aggie's bed and held
    her friend as close as she could. Aggie cried and cried, her
    whole body trembling. But after a while she calmed down and
    started breathing heavily. Teagan hugged her close and stayed
    there a little longer. It wouldn't do to be found in the wrong bunk
    in the morning, so she crept back into her own bed and tried to
    fall asleep.
    Aggie was a strong girl, but she'd just received the most
    dreadful beating in the long history of the Silo.
    The strange sound of an unseen monster weighed heavy on
    Edgar's mind as he crept forward ever so quietly. A warm, faint
    wind blew into Edgar's face. He assumed it was coming from
    the keeper of this place, a creature blowing gusts of hot air past
    sharp teeth, waiting for Edgar to arrive.
    He thought of Dr. Kincaid's words, the burning bridge of stone,
    and he began to wonder--could this be the very place? He was,
    generally speaking, at the end of the longest shard. And the
    monsters he'd encountered outside were the last thing he'd
    come to. Beware the keepers of the gate.
    "If it's true I've passed the keepers of the gate," Edgar said to
    himself, astonished at his own good luck, "then this must be the
    way to the docking station."
    He rose to his feet with some effort and peered down the long
    tunnel in which he stood. It led straight into the heart of
    Atherton, and it was dimly illuminated in a way he'd never seen
    before--with a kind of blue light.
    Where is that coming from? thought Edgar. He looked back at
    the opening of the tunnel and saw tiny blue dots dancing toward
    him. They were coming out of small holes in the ceiling and the
    floor. First there were ten, then a hundred, and then a thousand
    little blue bugs in the air.
    Edgar wanted to reach out and touch them, and he very nearly
    did. Isabel and Samuel had seen firebugs. They had known the
    allure of touching them, of wanting to join with them in their
    charming little dance.
    "I can see why Isabel wanted to touch them," said Edgar. "They
    are appealing little killers."
    The thousand firebugs became two thousand, and soon there
    was a thick fog of glowing cobalt between Edgar and the
    outside world.
    "Only one way to go now," said Edgar. He was afraid of what
    lay ahead, but he also knew that if even a few firebugs touched
    him he would never make it back to the surface of Atherton
    alive.
    Fortunately, the firebugs remained just a few feet beyond the
    opening. They appeared to be trying to come nearer to Edgar;
    the warm wind must have been too much of a struggle for their
    delicate wings. They hung in the air, fighting to stay aloft in the
    heavy gravity.
    It's really too bad they can kill me, thought Edgar.
    Now that his fate had been determined, Edgar forged on. It was
    an eerie feeling, walking toward the inside with no way of
    escape, and he dreaded the idea of dying there alone.
    Edgar's route turned into a climb again, though not a very steep
    one. When he neared the top the tunnel was glowing orange
    and yellow. Above him flowed a channel of liquid, a river of
    molten rock behind a ceiling of solid glass. The glass kept the
    river of fire from flowing into the tunnel where Edgar stood, but it
    seemed to Edgar that touching the ceiling could be hot enough
    to set him on fire.
    Without any warning whatsoever the warm wind stopped. All
    was perfectly still inside the tunnel for a few seconds as Edgar
    realized the danger of what had just happened. He was
    suddenly paralyzed with fear.
    "The firebugs," Edgar whispered. Soon he would be
    surrounded