Eren and Levi's new squad secretly set out to Shingansan district with the permission of Erwin Smith to find the basement of Eren's house. When they arrive, they discover something horrifying that could sabotage and wipe out the existence of humans once and for all. 

Can they stop the danger from breaching the walls before it's too late? Will the secrets of the titans actually be revealed? Will there ever be freedom for mankind?