Doon had been super-excited to go to the Pipeworks that morning. Finally, his chance to do something useful.
The whole place is damp, so Doon's issued some rubber boots and other gear for his work shift. A girl named Arlin shows him around and pairs with him on his first day in Tunnel 97.
Once they reach the Main Tunnel, Doon is surprised to come face to face with the river (he knows what the word means, but he's never seen one before).
It's a huge loud rush of water that powers the generator of Ember.
Arlin walks him through fixing a particular pipe that's leaking, and then she has lunch with her friends. Doon uses the time to check out the generator room, where he's not supposed to be without permission.
It's too loud to hear anything, and the old man Doon talks to just shoos him away. Doon is humbled—he's spent his life studying how things work, and the generator is clearly way beyond him.
He tries to talk to the old dude at the day's end, asking how the generator works. The man says nobody knows how it works, only how to try to fix it when it breaks down.
This is what Doon's thinking about when he sees Lina on the roof. He doesn't get how she can be so light-hearted, so he just trudges home.
He lives with his father over his father's shop, which sells odds and ends. Doon goes upstairs to their apartment and broods, like the budding teenager he is.
The more he thinks about his situation—how eager to help and smart he is, but without any clear idea of what to do—the more upset he gets. Angry, Doon hurls an old shoe heel at the door, because throwing stuff always solves problems (said no one ever).
At that moment, his dad opens the door, and gets hit in the ear with the heel.
Doon's father asks if he wants to talk about it. So Doon complains about his first day at work, and his father advises him to pay attention to the little things, and maybe he'll figure something out.
After their chat, Doon goes to his room, where he observes the worm he's been keeping in a box (Doon thinks bugs are cool and likes to study them).
Doon talks to his dad about the worm, and his dad encourages him to keep notes, and to look for interesting new bugs in the Pipeworks. Doon remains determined to accomplish something important there.