How did lina escape from the mayor?

lina finds the box in her closet that has the insructions the builders wrote for them to escape the city at the right time. but poppy chews them up and lina and doon figure ou what it says. they know the mayor wont do anyhing about it and when they trie to tell him he sent people chasing them and told people they were telling excesive lies. on the night everyone is singing and stuff they run into the pipeworks so noone will se them. and they go the way through the pipeworks the instructions told. they find candles and matches and boats. lina brings poppy. they ride through the river and find the place. then they realize the city of ember was undergound. the find a hole that leads to ember and send he instructions down the hole underground and it lands in front of someone.