Several hundred years ago, humans were nearly exterminated by Titans. Titans are typically several stories tall, seem to have no intelligence, devour human beings and, worst of all, seem to do it for the pleasure rather than as a food source. A small percentage of humanity survived by walling themselves in a city protected by extremely high walls, even taller than the biggest Titans. Flash forward to the present and the city has not seen a Titan in over 100 years. Teenage boy Eren and his foster sister Mikasa witness something horrific as the city walls are destroyed by a Colossal Titan that appears out of thin air. As the smaller Titans flood the city, the two kids watch in horror as their mother is eaten alive. Eren vows that he will murder every single Titan and take revenge for all of mankind.
After one hundred years of peace, humanity is suddenly reminded of the terror of being at the Titans' mercy.
After the Titans break through the wall, the citizens of Shiganshina must run for their lives. However, those that do make it to safety find a harsh life waiting for them.
Eren begins his training with the Cadet Corps, but questions about his painful past overwhelm him. When he struggles with a maneuvering exercise, Bertolt and Reiner offer kindly advice.
Two years pass and the time for the recruits' graduation approaches. Annie proves her skill in a sparring session, Jean dreams of serving alongside the King, and graduation day brings shocking revelations — along with the sudden appearance of an old foe.
Five years have passed since the fall of Wall Maria and Eren faces off against the Colossal Titan after it appears out of nowhere once again, and knocks a strategic hole in the gate of Wall Rose. As Titans swarm the city, the newly graduated Cadets are called in to fight a brutal battle that won't be without casualties.
Armin tries to cope with the loss of his friends and allies after Titans massacre his squad. Elsewhere in the city, Mikasa manages to take out several of the monsters, which brings back tragic memories of her past and the first time she met Eren.
After the retreat bell sounds, many cadets find themselves without enough fuel to scale the wall back to safety. Mikasa begins to lose hope once she hears of the deaths in Armin's squad, but the appearance of a new type of Titan stokes her will to fight.
Armin comes up with a risky plan that pits Titan against Titan as the abandoned cadets attempt to take back their headquarters. Getting into the building might be possible, but getting out alive and refueled will mean facing more of the giants.
A miraculous return is met with anger and fear. Cannons are fixed on Eren as he struggles to remember what happened to him inside the belly of a Titan and how he ended up as humankind's enemy. One question is all that matters: is Eren human or Titan?
Cadets respond to Eren's terrifying transformation with doubt and fear as he struggles to understand it himself. If Armin can’t talk the commander into using Eren’s newfound powers for the good of humankind, all hope of stopping the Titans might be lost.
Plans are made to use Eren's Titan powers to seal the hole in the wall in an attempt reclaim Trost. But with the government's bloodstained history and vocal dissenters in the military ranks, the biggest threat to humankind may not be the Titans.
The plan to reclaim Trost falls apart when Eren's newfound powers turn him into a mindless giant. As Titans continue to swarm the city, it's up to Armin and Mikasa to make sure the cadets massacred during the mission haven't died in vain.
Jean takes desperate measures to replace his broken Maneuver Gear. Meanwhile, Eren is able to seal the hole in the wall thanks to the help of his fellow cadets, but the cost of humanity's first victory against the Titans will be enormous.
A special military tribunal will decide Eren's fate. The Military Police calls for his execution while the Recon Corps argues that he is a powerful resource for humankind, and Mikasa is put on the spot when asked about the events of the Trost mission.
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.
The Female Titan has captured Eren after ripping him out of his Titan body, but Mikasa and Captain Levi give chase. Elsewhere, the Recon Corps begins preparations for the journey back home to the Wall with their numerous dead in tow.
Following the disastrous results of the 57th Expedition, Eren is to be brought to the King’s palace for a court martial. Armin, desperate to save Eren from certain execution, enlists the help of an old friend to assist with an escape plan.
With the identity of the Female Titan now revealed, Eren has reservations about fighting her. Mikasa, Armin, and the rest of the Recon Corps try to fight the Female Titan, hoping to distract her long enough to buy Eren time to come to terms with his feelings.
Eren, spurred on by his promise to kill every single Titan, unleashes the full power of his Titan form in the fight with the Female Titan. As their bloody battle draws to a close, it seems humanity may finally have a chance at survival. However, with many mysteries still left unsolved, what will await Eren, Mikasa, and Armin?