Lina couldn't sleep at first, thinking of the old songs and what they meant. Someone, long ago, had hoped that at least a few people would survive and had wanted them to remember her city and the treasure it held, the treasure that was most valuable of all - herself, her family, and all of the generations of people who had lived in that secret place, their purpose, though they didn't know it, to make sure that human beings did not vanish from the world, no matter what happened above.

Now Doon seemed to care for his new friends more than he did for her. Every time she thought about him she felt a thud of pain, like a bruised place inside her.

A person who thought he knew everything simply didn’t understand how much there was to know.

The main thing to do is pay attention. Pay close attention to everything, notice what no one else notices. Then you'll know what no one else knows, and that's always useful.

Lina loved her little sister so much that it was like an ache under her ribs.

Remember the city, the city remember Where treasure is hidden under the ground The city, the city, always remember That's where the treasure will be found.

His sympathy made tears spring to Lina's eyes. Doon looked startled for a moment, and then he took a step toward her and wrapped his arms around her. He gave her a squeeze so quick and tight that it made her cough, and then it made her laugh. She realized all at once that Doon--thin, dark-eyed Doon with his troublesome temper and his terrible brown jacket and his good heart--was the person that she knew better than anyone now. He was her best friend.