the female titan, she was destroying the whole city. Annie leonhard. After she was outed as the female titan. Confirmed by armin alert, they had a mission. But it failed all. After they tried to convince Annie to come with them into the tunnel. She transformed into the female titan. You have to fight her before anything bad happens. Eren. He still didnt transform. You have to fight her. Until he manages to transform and take things into his hands.