NOTE: This spoiler was submitted by Spectre.
We open in the arctic wilderness. A large moose is walking along. In the trees, a young girl decked head to toe in camouflage stalks him with an arrow. She waits for the right moment and shoots at the moose. It hits, and the animal runs off in fright. The girl gives chase and follows it to where it has collapsed from the trauma. She looks into its eyes, and pulls down her scarf. "I just missed your heart." says Hanna (Saoirse Ronan). She pulls out a German Luger pistol and shoots the moose dead.
As she begins to carve into the animal and remove the entrails a man comes up behind her. "BANG." he says. "I've killed you." Hanna turns around and flings the knife, which the man deflects. "Use your hands." he says. Hanna charges him and they begin to spar culminating with Hanna getting him a headlock. The man pulls her off and flips her to the ground. "Get home on your own." the man says and walks away. The man is Erik Heller (Eric Bana), Hanna's father.
Hanna carts the animal carcass home in a makeshift sled, her father shadowing her every step of the way. When she gets home, her father said she was half asleep out there. Hanna says she will do better next time. Later that night, Erik is reading to his daughter, speaking about Blue Whales and the song they sing. Hanna asks about music and her father gives her a dry explanation from the book. Hanna says she would like to experience music for herself. Erik denies the request says they have enough here.
Hanna is sleeping when a lone figure holds a gun to her head. She snaps to attention, and subdues the man. It is Erik who wanted to test her again. Hanna tells her father that she is ready to do their mission. Erik asks her what her cover story is, and she rattles it off from memory; where she lives, where she goes to school, who her friends are. Erik nods. She is ready.
During the night, Erik counts his steps outside and digs until he finds a steel box.
Hanna is out the next day training, when she sees a plane fly above her. She screams in fright as she hasn't seen anything of the real world. She goes back to the cabin and tells her father. He is waiting for her and shows her a transponder. If she turns it on, the target of their mission Marissa (Cate Blanchett) will know where they are. Hanna is warned not to flip the switch until she is ready because Marissa will not stop until Hanna and Erik are dead. Erik tells her to take her time.
The next morning, Erik wants to hunt and asks if Hanna wants to go. Hanna says she'll go if he wants her too, but he wants it left up to her. She decides to stay. She sits and looks at the transponder for a long time and flips the switch. "Come and find me." Hanna says.
On the other side of the world, Marissa wakes up and brushes her teeth, she has many dental tools to keep her teeth perfect. When she walks in the CIA (where she is apparently a high ranking member) she is told that they intercepted a signal, and they think it is Erik Heller. Marissa calls a meeting.
There we find out more about Erik. Erik was a CIA agent that went dark years ago. His last recorded movements where in 1996, when his prints were found a Luger that killed a woman named Johanna. Marissa says they need to extract Erik. The other men scoff, saying they have more important things to do, and that Interpol should pick him up. Marissa counters that Erik knows all their dirty laundry and he cannot fall into the hands of any other government. They agree to extract him.
Erik comes home and says Hanna was right to stay home, he didn't find anything out there. He sees she tripped the transponder. He nods. It's time for him to go. They cut his hair and shave his beard and get him into a nice suit. Within an hour they can hear the plane coming. Erik leaves, telling her he will see his daughter in Berlin after Marissa is dead. He tells Hanna to remember what he taught her.
A special ops squad surrounds the cabin and two soldiers go inside. There is no response, so the entire squad enters. They find the two soldiers dead and Hanna nearby.
Marissa gets a call from the squad commander. He says Heller got away and killed two of their men. They was also a young girl there.
Hanna is taken to a remote bunker and placed into a containment room. A psychologist tries to ask her some questions about her father, but she is unwilling to answer any. Hanna notices the cameras, and the psychologist confirms that the are there. Marissa is watching on a screen as this is going on. Hanna says she wants to see Marissa Veigler, which shocks Marissa that Hanna knows who she is. Marissa tells the techs to tell Hanna she will be there tonight.
A woman walks into Hanna's cell claiming to be Marissa. She's not; just a double who is being feed the correct answers to Hanna's questions by the real Marissa. Hanna breaks down in tears and the fake Marissa consoles her. The techs tell her to keep her distance but she doesn't listen. The psychologist and two guards come to sedate Hanna but she is ready for them. She quickly snaps fake Marissa's neck, then flips a guard coming in. Grabbing his gun, she shoots the two guards and the doctor with a bullet in the eye. She then uses the rest of the clip, to shoot out the cameras. Marissa watches the entire thing, startled.
The base is being locked down but Hanna is not worried. She runs quickly, ducking under a closing hatch door. Using the ventilation system, she evades the numerous guards that look for her. She jumps down into the lab and holds two scientists hostage in order to get out the right door, but not without grabbing her genetic file first. Hanna climbs up another shaft and finds herself in the middle of the desert.
Hanna sees some Humvees driving right under where she has come out of. After timing their speed, she grabs onto one and lets herself be carried. She cannot hold on for long though, and has to let go, using the dust as cover. Unsure of where she is, Hanna begins to walk.
Marissa goes home and opens her safe. She pulls out money, passports, and a file titled "Galinka". She burns it in the kitchen as we flash back to Hanna as a child. Her mother Johanna was with Erik, who was driving. Marissa was nearby with a gun. As they moved closer, Marissa came out of hiding and emptied the clip into their car making it crash and catch on fire. As she investigated, she saw the car was empty. Turning to the forest, she saw three figures which she fired at. She only hit Johanna. Erik and Hanna escaped to the woods. Marissa confronts the dying Johanna who tells Marissa "You will never have her." Marissa finishes her off. She killed Johanna NOT Erik.
Hanna is walking for quite a distance when she becomes across a young girl like herself. The girl asks if she knows English and its OK if she didn't. The girl, Sophie (Jessica Barden) says that artist M.I.A.didn't know English for years because she was a refugee. Sophie's brother Miles asks about the girl and Sophie's says she doesn't speak English. Hanna then speaks, confirms she speaks English, then rattles off her cover story. Sophie just nods, weirded out.
Erik meanwhile is near a river, and strips down to his underwear, putting his suit in a bag. He begins to swim.
Marissa is on a plane, telling her subordinate that they need to concentrate their priorities on Erik Heller. He is the more direct threat right now. She disconnects the phone and sighs.
Hanna is watching Sophie with her family. Sophie asks if she needs a ride somewhere but Hanna says she will walk. Sophie and her family drive off.
Erik finds himself at a dock. He barely gets out the water before two cops find him and begin to walk towards him...
Hanna finds herself at a river stream where she sees several women, singing and dancing while they wash their clothes in the water. Hanna is transfixed by it and steals a cloth to wear over her jumpsuit. She gets into town and watches people, unable to comprehend the culture around her.
She goes to see a man, and asks where she is. She finds out she is in Morocco. Knowing the man is Arabic, she begins speaking in that language. She says she needs a place for a night but cannot pay. Sensing she is in trouble the man gives her a room for the night. Hanna is in awe, never having electricity before. The man turns on a television and Hanna asks what it is. He misunderstands her question (she's never seen a television before) thinking she is asking about the programming. He leaves her, and Hanna becomes overwhelmed by this new stimuli and runs out of her room, right into Sophie who is surprised that Hanna is in the same place. Sophies rattles on about wishing that she could be a hot lesiban which only confuses Hanna.
We cut back to the dock where Erik found himself. The body of one of the cops is being pulled from the water. Erik killed them. One of Marissa subordinates Lewis says he talked to Interpol as with Erik killing cops it has got out their hands. Marissa scolds him telling him they will contain it, and not to question her again.
Hanna has dinner with Sophie and her family. Her parents are a pair of beatniks that take an unconventional but loving stance to parenting. Sophie's mother Rachel (Olivia Williams) asks about Hanna's parents. Hanna says she is meeting her father in a few days. When pressed about her mother, Hanna says she died "by three bullets". This greatly disturbs the family, but Hanna says she is fine with it as it happened a long time ago.
Marissa goes to a club called Safari. She meets with the club owner Issacs (Tom Hollander), who is an off the books wet work asset. Marissa says she needs Hanna found and Issacs can "do things my agency won't allow me to do." She hands him information and some cash, telling him to find her. When she leaves, Issacs asks Marissa if "she" (Hanna) turned out as good as she hoped. "Better." Marissa says.
The next morning, unknown to Sophie or her family, Hanna has snuck in their RV and is hiding. She watches them sing and look happy and is in awe of the family. For a moment it looks like Miles has discovered her, but he just motions her to be quiet as he knew the whole time (he has a crush on her).
Issacs go to the Moroccan hotel with his skinhead henchmen and tortures the owner who gave Hanna a room. The owner says she was just a girl that needed help and he gave her a room for the night. One of his henchmen sees Hanna get onto Sophie's RV. Issacs asks if they checked out, and the man says they left onto a ferry to Spain. Issacs asks for the man's pen, then uses it to stab him to death.
Erik is holing up in a house holding a postcard sent by Hanna stating (incorrectly) that Marissa is dead. He smiles.
Hanna wakes up in the RV after it has made a complete stop. She is trying to decide the best route, and Miles directs her to go out the back. Hanna runs off; she is in the middle of a campground. She winds up finding herself at an outdoor pool and begins to drink the water. Sophie pops up and says she needs Hanna's help; their are two cute boys that want to hang out and Hanna needs to come. Hanna agrees to the request. Sophie is surprised and promises to get Hanna new clothes so she can look nice.
Meanwhile, an old woman comes home to find Marissa in her apartment. She is Johanna's mother, and thus Hanna's grandmother. Marissa asks where Erik is. The woman says Erik told her Marissa was dead by letter. Marissa asks about Hanna's whereabouts. The woman asks if Marissa has children. Marissa said she made "certain choices." The woman tells her that then she will never know the pain of losing a child. Of not knowing why. Marissa pulls out a gun in full view of the woman and attaches a silencer. The woman accepts this; she is old and she knew she wasn't going to be spared. She looks at the picture of her daughter and asks what Hanna looks like. A shot rings out, and she crumbles to the floor dead. Marissa replies, "Like her mother."
Hanna and Sophie ride on motorcycles with the two boys. Hanna is clearly enjoying the new experience. They watch a live performance of music and Hanna listens attentively. Sophie begins to make out with her boy while Hanna notices. Later, Hanna asks the boy she's with if he is going to kiss her. He asks if she wants him to. Hanna then states that you use 34 muscles during kissing. The boy tries to kiss her but her training kicks in, and she almost snaps his neck. Sophie sees this and makes her stand down. Sophie and Hanna leave.
Issacs and his henchmen find the camp and search for Hanna and don't find her. They pull back and wait.
Hanna and Sophie have returned to the camp and talk under the covers. Sophie says Hanna has to be honest if they are going to be friends. Hanna says she would like a friend. Sophie tells Hanna she likes her even if she is a bit weird; Hanna echoes her sentiments. Problem is, there are certain things she cannot explain. She shows Sophie the genetic report and says she cannot understand why she is different. Sophie gives her a friendship bracelet to remember her by, and Hanna lets her defenses down and softly gives her first kiss to Sophie, which makes Sophie blush and smile.
The next morning, Rachel and her husband Sebastian (Jason Flemyng) discuss Hanna and her father. In the meantime they will let her go with them until Hanna can get to Berlin. Hanna shows up with a skinned rabbit for breakfast, which disgust the family.
Meanwhile, Erik has made it to Berlin, getting off a bus. As he passes through the station, we see that men are tailing him. But Erik is not as clueless as we think. He knows that something is up. He goes down an escalator into the subway station. There he is surrounded by five agents. They go to grab them, but Erik successfully defends himself, knocking out several agents, having one be shot by his own teammate, and throwing a knife into the final man. Erik hears a radio cackle, saying the men has to extract Heller to Marissa Veigler. Erik poses as one of the agents and confirms this. Erik is worried; Marissa is still alive.
Hanna is sitting up with Rachel as she drives the RV. Rachel tells Hanna she hates the city, and only by traveling does she feel truly alive. Hanna notices Issacs and his men tailing the vehicle, but tries to dismiss it as nothing.
Marissa is in her hotel room with Lewis when she gets a call from Erik. She plays aloof and calls for tech support. She asks why Erik came out of hiding now as they hear a knock on the door. Lewis looks through the peephole and is shot in the face. It is Erik, coming to kill her. Marissa returns fire a few times before escaping through the hotel window.
It is now nighttime. Hanna is still watching the car with Issacs in it and realizes they are not leaving. They are being followed. Unfortunately, Rachel is lost and has to pull over in order to see the map. Hanna knows she has to go, and makes Sophie promise not to follow her which she agrees to. Hanna bursts out the back door while Issacs and his men chase her.
They play a cat and mouse game in a shipyard until Hanna confronts both of the skinheads and begins to fight them. One tries to pull a knife, but Hanna disarms him and uses it to stab him and slit his throat. Sophie witnesses the entire thing and runs off horrified that her friend is a killer. Hanna cannot do anything about that, so she Hanna jumps on top of the containers and is followed by the other skinhead. She is able to escape where he cannot follow. Issacs catches up to her however, and she is forced to jump into the water.
Issacs and Marissa have taken Sophie's family hostage, pretending that Hanna is a dangerous criminal. Sebastian can't give Marissa any pertinent information. Rachel just says Hanna was a girl that looked like she needed help. Sophie will not tell Marissa anything. So Marissa uses Miles' crush on Hanna against him to spill that Hanna is going to Berlin to meet her father. The family's fate after that is left unknown.
Hanna makes it to where her father wanted to go, which was an abandoned golf course/theme park. She meets her father's contact who she nicknames "Mr. Grimm." (after the fairytale book her mother gave her as a child). The man is nice to her and gives her a passport and money that her father set away for her so they could disappear. He gives her an address her father wanted her to meet at.
Suddenly, Issacs shows up and the man orders Hanna to hide upstairs. Issacs bursts in and begins to interrogate him.
Hanna is under the bed upstairs when she sees Marissa come up next to her. Marissa gets a call from her bosses. They are livid on her failure to contain things; Lewis has been killed, several other agents dead etc. Her career is on the line and she needs to stop. Marissa bets it all however, and tells them she will not stop. Issacs comes up, saying the man knew a little about the program and truly believes Erik is Hanna's father. Hanna is stunned by this revelation. Marissa looks under the bed but finds nothing as Hanna perched herself in the framing. They leave.
Hanna goes to her grandmother's apartment where she sees the bloodstain of where she was murdered. Erik shows up soon after and Hanna confronts him and demands the truth. Erik explains it all. He was a CIA operative who worked on a genetic project to tweak fertilized embryos in order to make better soldiers. He recruited women from abortion clinics like her mother. Two years into the project, Marissa Veigler scrapped the project, and eliminated all the mothers and their children. But Erik conscience would not allow that to happen to Johanna and Hanna. So he took them into hiding but Marissa found them.
Hanna is crushed Erik is not her real father but he says he is; he took her in and loved her as his own. She is his child, genetics be damned. Hanna wants to leave, but Erik says they are not done. They begin to fight each other and Hanna runs outside. Erik meets her and says he tried to prepare her. Hanna says he didn't prepare her for this. Out of nowhere, they see Issacs show up. Erik tells her to RUN.
Hanna runs away, while Erik races off in another direction to draw Issacs away. Erik jumps into traffic causing a crash or two. Issacs' second henchmen catches up to Erik in a playground and they fight. Erik kills him as Issacs sneaks up behind with a pipe. Erik disarms Issacs then impales him with the pipe. Erik turns around and sees Marissa there holding a gun.
Erik collapses, exhausted and beaten. He knows he cannot get away this time. Marissa asks him why he came out of hiding now after all these years. He replies, "Kids grow up." his way of saying "go fuck yourself." She raises the gun.
Hanna is still running when she hears the shot. Her father is dead; he gave his life to save her. Now she has no one.
Hanna goes back to the house of "Mr. Grimm" to find him strung up with arrows jabbed into his chest. She grabs one and looks around. Looking out a window, she finds Marissa there. She races out of the house and runs around the golf course, grabbing a taut piece of rope along the way.
Near a golf hole with a wolf's head alleyway she is confronted by Marissa. Marissa puts her gun away and says she just wants to talk. Hanna says it is over, she doesn't want to hurt people anymore. She's done. She turns to walk away. Enraged, Marissa raises her pistol saying "Don't you turn your back on me young lady!" Hanna turns around and uses the rope as a bow string to shoot an arrow at Marissa who in turn fires a single shot. Both get hit.
Hanna grimaces in pain but gets back up and follows the wounded Marissa. She follows her into a warehouse where Marissa fires wildly trying to get Hanna but she dodges the shots. At the top of the structure, Marissa goes to fire but her heels slip on the wet ground and she falls down a large slide, dropping her gun.
Hanna slides down and takes the pistol. She looks at the dying Marissa and says "I just missed your heart." Hanna raises the gun and finishes her off.