The book contains a journal entry, written by an old woman who talks about having packed her suitcase for the trip. They're not supposed to bring anything that shows the world they came from; no photos or maps.
She's determined to chronicle her journey, though, in case someone needs to know about it in the future. Good move, lady.
They spend a long time on the train. The trip is supposed to ensure the future of humanity in case disaster strikes. This is all sounding not so good.
There are fifty men and fifty women in their group, all above sixty years old. They're randomly paired into couples, and each couple gets two babies to adopt.
She pauses the journal entry because the babies are being brought in.
The writer has a baby girl on her lap, and Stanley (her new mate) has a boy on his lap. They name the children Star and Forest.
They have a long journey underground, to where the boats wait. The writer finishes up her journal entry, hoping that no one notices.
The journal entry ends there. Lina and Doon wonder what the disaster was that was supposed to have happened. Then they wonder if there's another way to get back to Ember, since the boats won't let them return up the river.
As they're looking around, they see a strange and awesome-looking creature (they have no idea what it is, but from the description we can tell that it's a fox).
Because the creature was eating something that looked like a wrongly colored peach, they decide to look for some of those fruits because they're probably safe to eat.
Next, they discover a tunnel. When they explore it, they find a sheer ledge that drops into the darkness. But it's not completely dark—far below is a cluster of light. It's Ember.
The kids realize that Ember has been underground this whole time. Maybe they can still get a message to the people if they drop it down through this crevice.
Lina takes the note she'd intended to deliver to Clary, and adds a section about how they've found this new place where light comes from the sky, urging everyone to join them.
Then they wrap the message and a rock in Doon's shirt, and throw it into the city below.
Mrs. Murdo is out walking when the bundle falls at her feet. She begins to untie it.