Christina comes along to help Tris. They hop into a pickup truck with Marcus, roll the windows down, and cruise.
Christina and Tris pretend to be Abnegation and Amity, and the guards just let them roll right into the city.
At Amity headquarters, Tris and Christina meet up with Johanna, that woman Tris thinks would be super pretty if it weren't for that gnarly scar screwing up her face.
Tris tells Johanna what's going down—that the Dauntless and the factionless will destroy Erudite—and she asks to speak to the Erudite Johanna is harboring in the compound. Johanna agrees to let her see them tomorrow.
The next day, Tris ends up walking right smack into an Amity religious ceremony. All the love and peace and friendship freak her out (no, really, that's what happens), and she runs away.
Later, Johanna calls a meeting to tell all the Amity about the big ol' storm that's brewing.
Johanna says that whether or not the Amity decide to help, she will help. She is stepping down as a representative of Amity, and anyone who wants to help can come with her.