Grin

 is the 1st chapter of the 8th volume and the 31st chapter overall of the Attack on Titan manga, written and illustrated by Hajime Isayama.

Overview
Annie awakes in her room within the Stohess District. While the citizens grow nervous due to the oncoming arrival of Eren, Annie and the other MP recruits are given the mission to protect Eren and the Survey Corps as they pass through town. Marlo Freudenberg, a young soldier, is put in charge of the missions details because his superior officer singled him out for asking a question. He then gets angry, saying that the Military Police is full of lazy scum. Some other soldiers then begin to make fun of him, but Annie defends him saying that he is indeed a righteous person. When the operation begins, Annie is found by Armin who asks her to help Eren escape. She initially refuses but then accepts when she is told that he would be killed. She then travels with Armin, Eren, and Mikasa and they tell her to enter to a tunnel, but she refuses. After much debate, the three reveal that they know her identity as the Female Titan and she gives a disturbing grin, saying that though they may have won their bet, hers begins now.

Summary
In the Stohess District, a few citizens have a conversation about the previous day's events. They get news that Eren will be passing through the town later in the day to be handed over to the Military Police. Another worries that officials will use him to influence the King, while another still wants them to seal up the Wall regardless. Upon hearing this, a fanatic member of the wall worshiping religion accosts him, saying that to seal the wall would be blasphemy.

Elsewhere, Annie wakes up late and meets the other members of the police force who are already at attention and ready for the day's instructions. Hitch and Marlo give her a hard time for being late, before Boris Feulner reminds them that she was present for the attack in the Trost District, suggesting that she's still recovering. Moments later, a senior officer walks in and gives them their orders for the day. Annie's interest is piqued when she hears that they will be escorting members of the Survey Corps on their way to the capital. Marlo questions the need for an escort. Not wanting to be bothered with the responsibility, the officer leaves Marlo in charge with a warning to not mess it up.

Outside, Marlo complains about the attitude of the senior officers. He states that he wants to advance in the Military Police Force, so that he can change it from the inside. After some jokes and insults from the other soldiers, Annie speaks up. Hearing his speech, she is reminded of Eren and commends his courage for going against the majority and says that it's rare. She also tells him that most of the trainees are what he would consider scum and trash as they would put their own personal gain above others, even placing herself in that category, but that they are what is normal. Her speech causes Marlo to rethink how to change things.

As Annie walks through the town, Armin quietly calls out to her, hidden in an alley. Seeing that she's officially in the police force now, Armin asks her for a favor. He wants her to help in his plan to get Eren out of the city. At first, she refuses, thinking the plan isn't well thought out. After a heartfelt argument from Armin, Annie finally agrees.

Wearing heavy raincoats with hoods, Mikasa, Eren, and Armin make their way through the city, escorted by Annie. The trip goes smoothly thanks largely to the Military Police's lack of attention to detail. However, they still have to hurry before the cart reaches the capital and they find out that Jean has taken Eren's place as a decoy. Curious, Annie asks Armin how they would have escaped had she not agreed to help. Armin reveals the reckless plan of using 3-D maneuver gear. Reaching an underground tunnel, they start down the stairs but Annie doesn't follow. Eren turns to ask what's wrong. She gives an unconvincing argument that she's just a scared, frail maiden and that he wouldn't understand. Eren, recalling her aptitude in hand-to-hand combat remarks that she can't be that frail and insists that she come down. Still refusing, she says that if they go underground, her escort stops there. Angry, Eren yells for her to stop messing around with Mikasa trying to quiet him. Annie, becoming suspicious, says that his yelling doesn't matter, as they haven't seen a single person on the streets since they got to the tunnel. Another view reveals that members of the Survey Corps are hidden on rooftops and in the shadows of the nearby buildings.

Her suspicion coming to a head, she feigns insult at the realization of Armin's real plan. Armin questions her about the equipment she was using, confessing that he knows it was Marco's. He also tells Annie that he knows she was the one who killed the Titans, Sonny and Bean, being used for research by the Survey Corps. She asks why he never said anything until now. Armin explains that he didn't want it to be true; he was hoping that his train of thought had messed up somewhere. Armin also acknowledges that he knows she is the Female Titan and in turn, asks why she hadn't killed him in the field the day of the mission. Eren, offering redemption, says that all she has to do is come with them now. Fed up with Annie's games and realizing that the conversation is going nowhere, Mikasa takes off her rain coat and readies her weapons. She calls her out as the Female Titan that attacked them earlier and won't let her escape. With the secret out, Annie gives a big grin and prepares to take on her Titan form. While Eren and Armin are shocked, Mikasa takes her stance, prepared to fight Annie.