Wall Sina is the only wall left. Annie's Crystal has broken, but it's pointless. She won't speak. Hange and Levi can't make her transform, either. She doesn't want to, so she won't. Their last resort is to get all of the 104th training corps together, and try to persuade her.
It was proven that Armin's claim of Annie being the Female Titan was correct. But even though it was Armin who helped solved this mystery, he can't help but notice his feelings for Annie along the way. And after what they've been through together, Armin will realize that there are two different sides to every story.