The Recon Corps moves Eren to an old abandoned castle where he will continue his training. Hange visits and reveals that she's been putting two captured Titans through a series of tests and trials — experiments that she wants Eren's help with.

Everyone is a suspect in the investigation to find out who killed the two test-subject Titans. Meanwhile, the cadets pick which military branch they'll be joining, but after the harrowing events in the Trost attack, many are uncertain which branch to choose.

As the Recon Corps begins its push toward Shiganshina, they encounter an intelligent Female Titan unlike any they've seen before. When Armin hypothesizes that it's really a human that's been turned into a Titan, he, Jean, and Reiner attempt to stop it.

As the Female Titan continues to tear its way through the Recon Corps, Levi makes a bold decision to split the ranks and send Eren and the supply wagons through a huge forest. Is his strategy genius, or does it spell certain death for the scouts?

With the Female Titan still chasing after Levi's squad, Eren considers turning himself into his Titan form, but Levi tells him to choose to be either a monster or a member of the Recon Corps. As Eren remembers what he has learned from the squad, he realizes that the danger and sacrifice they all share is not what binds them — it is trust. Now it is up to Eren to make the decision of who he will trust.

With the help of Levi's squad, the Recon Corps has successfully captured the Female Titan. As Commander Erwin and Captain Levi begin preparations to extract whoever is inside the Titan, will the Recon Corps discover its true identity, or does the Female Titan have one last trick up its sleeve?

After a last act of desperation, the person inside the Female Titan has escaped from the Recon Corps and reverted to their human form. Now, disguised as a member of the Recon Corps and equipped with Maneuver Gear, they finally catch up to their prey — Levi's squad.

Hange is insistent on capturing a Titan for the advancement of scientific research, but Erwin is adamant in his refusal to allow it. Will an unexpected discovery during an expedition beyond the walls alter the situation?