Unarmed and overwhelmed by the Titan assault on the castle, the only hope for the Scouts may lie in a promise and a secret.

Utgard Castle comes crumbling down as Ymir desperately battles the Titans. Now, Christa must fulfill the promise they made long ago during winter training.

When their group finally flees, Ymir wonders whether she should lie or stay true to herself, even if it means ruining the lives and future of those she cares about.