To take revenge on humans, the dog king has gathered hundreds of stray dogs. He is leading his entire army to attack the city, but unexpectedly meets his little owner. .
. Thirteen-year-old Lili is an introverted girl who is experiencing troubles with transitioning to adolescence. Ever since her parents divorced, she has had a hard time getting along with them.
Her only friend is a ginger mutt named Hagen who she spends all of her free time with. Lili’s mom is going to go to Australia on a business trip and asks her ex-husband Daniel to look after their daughter and her dog. He works at a slaughterhouse, and the last time he saw her daughter was when she was still a child.
Daniel is not quite happy about having a dog in his house, however he is willing to sacrifice his comfort for Lili. Completely unaware of what his daughter likes, Daniel gifts her a bottle of soap bubbles. When they enter the house, Daniel’s landlord tells him that the dog can’t stay in the apartment.
The man tries to talk the woman down saying that Hagen won’t stay there for long. During dinner, Lili plays with the dog and feeds him the food she stole from the table. This behavior annoys Daniel even more and he scolds his daughter for breaking the rules in his house.
At night, Lili wants to have Hagen sleep in the room with them, however her father is against it, so he locks the dog in the bathroom. Hagen whines in anguish all night, keeping Daniel and Lili awake. To calm her pet down, the girl comes over to him and plays the Hungarian Rhapsody №2 on the trumpet.
Hagen quickly falls asleep to the calming music, and Lili lays down next to him in the bathroom. In the morning, Daniel wakes up to a knock on the door. An animal control inspector pays a visit due to complaints from the neighbors.
Daniel tries to conceal Hagen’s presence in the house, but in that moment the dog leaves the bathroom. The inspector lets him know that according to the new law, Daniel needs to pay the tax for keeping an unregistered stray dog. The man becomes furious and refuses to pay money for his ex-wife’s dog.
Having overheard their conversation, Lili begins to worry that her father will send her pet to the animal shelter. To not leave Hagen home alone, she brings him along to her music school and hides him in the storage room. Due to the loud music, the dog runs out of the storage room and disrupts the class.
The infuriated teacher demands Lili take the dog out of the classroom and get back to class. But the girl does not want to leave her friend alone, so she leaves with him. On her way home, Daniel catches up to Lili in his car.
The music teacher called him. He yells at his daughter and insists that they take Hagen to an animal shelter. The girl doesn’t want to say goodbye to her best friend and tries to persuade her dad to pay the tax for him, but the man remains adamant.
He stops the car and throws Hagen into the street, despite his daughter’s tears and desperate pleas. The dog attempts to catch up with the driving car, but he can’t keep up with it. So he ends up all alone in the middle of a busy highway.
At night Lili plans on searching for Hagen and looks in the refrigerator for some meat. Her father busts her in the kitchen and sends her back to sleep. For many hours, the dog faithfully waits for his owner at the same spot where he was abandoned, but she never comes for him.
Hagen decides to go look for food and finds a dog that was hit by a car on the side of the road. He contemplates for some time whether he should eat one of his own kind, and in the end, he decides to look for different food. Following a scent, he finds a butcher’s shop and hungrily stares at the meat.
All of a sudden, his attention is drawn to a little white dog who tells him to follow him. He takes Hagen to a backyard of the market, where a few other dogs are finishing up the remaining meat. But when Hagen tries to get closer to the food bowls, other dogs start to bark at him.
The butcher comes running to the noise and tells the dogs to go away. Hagen stays where he is and barks at the butcher, which angers the man even more. The ginger dog hides from him in the cutting room, but the butcher, armed with a knife, finds him there and plans to stab him to death.
The white dog comes to Hagen's rescue, grabs the man by the leg and saves Hagen. His new furry friend takes Hagen to an abandoned yard, where the rest of the stray dogs joyfully jump through puddles and drink water from them. The ginger dog also tries to join the pack, but the dogs do not accept the stranger.
So Hagen and his white friend have to watch the pack from a safe distance. The next day, the dog trapping service finds the place, and the friends again have to flee to avoid being caged. Hagen is cornered by two catchers and the friendly dog moves close to one of them.
But the white dog warns Hagen of the danger, so he squeezes through the bars and escapes. Trying to hide from his pursuers, Hagen runs through the alleys of the city and finds shelter with a homeless person. When the employees leave, the man feeds the gullible dog and puts a rope around his neck.
Daniel takes Lili to a music school and forces her to apologize for her behavior. The girl convinces her father and teacher that she will no longer look for the dog and that she realized that he was nothing but trouble. However, after class, Lili goes to the place where they left Hagen the day before, but does not find her pet there.
The girl doesn’t give up and continues to look for the dog in the neighboring streets, while hanging up missing posters everywhere. That same evening, a homeless man sells Hagen to a restaurant owner in exchange for a few bills and a plate of food. The man turns out to be a dealer who illegally sells stray dogs.
The next morning, a customer named Szabolcs comes to him to choose a dog to take part in the fight club. The dealer offers him one of the big, aggressive dogs, but the buyer chooses Hagen. The man tries to talk the customer out of taking Hagen and warns that the dog's skin is too thin and he is too kind to participate in such things.
But Szabolcs is confident that he will be able to make a fighting dog out of him before the next match. He feeds the dog sleeping pills to take him to his house. When Hagen wakes up, the man feeds him a protein supplement mix to build up his muscles.
To instill aggression in the dog, Szabolcs regularly beats him with a whip and subjects him to exhausting training. Soon Hagen loses the remnants of his friendliness and turns into a cruel beast that is ready to tear his opponent to pieces at any moment. Meanwhile, Lili does not stop searching for her pet.
She arrives at the animal shelter and asks the owner about Hagen. The woman says that the dog has little chance of surviving on the street. Most likely, he has already been hit by a car, or has drowned in the river.
While the girl was in the shelter, her bicycle was stolen, and she ended up stranded alone far from home. At night, Szabolcs takes Hagen to an underground dog fight club to test his new subject. The rules of the fight are simple: two angry dogs fight against each other in the ring and the one that remains alive wins.
The owner of the champion dog wins the big jackpot. Hagen is released into the arena against a large black Rottweiler. A fierce fight begins between the dogs, during which the ginger dog at first is losing to his rival.
But at the decisive moment, Hagen gnaws through his opponent's throat and wins the match. As his trainer rejoices in his victory, the ginger dog blankly stares as the bloody Rottweiler is carried out of the arena. Admiring Hagen's abilities, one of the spectators tries to buy the dog from the owner.
When Szabolcs refuses to sell his subject, the men begin to argue. Suddenly, the lights go out in the room. Szabolcs thinks that someone has stolen the dog, but Hagen, taking advantage of the moment, runs away from his tormentor.
At the same time, Lili runs home through the night streets. She accidentally bumps into Peter, her classmate from music school. The girl isn’t in a hurry to return to her father, so she asks Peter to take her to a nightclub with him.
At first, the guy refuses, but later decides to use Lili to sneak a bag of weed inside the club. The teenagers enter the club as a couple and the security guard quietly lets them through, despite the girl being too young. Once they are inside, Peter leaves Lili alone at the party while he goes off to have fun with some older girl.
She gets jealous and decides to get drunk, which maker her fall asleep right on the floor of the club. In the morning, the police come to the club and find the weed on her. They take Lili to the police station, where she takes a drug test.
The test turns out to be negative and law enforcement officers hand over the girl to her worried father. Daniel cries, feeling guilty about what could have happened to his daughter. He apologizes to Lili and offers to adopt another dog from the shelter.
The girl forgives her father and says that she no longer wants a dog, so they return home. The next day, Daniel has to go to work, but he is afraid that Lili will run away from home again. The girl promises him that she will not run away and persuades her father to go.
Meanwhile, Hagen returns to an abandoned puddle yard where he finds his old white friend. They play together near the river and look for leftover food, but their quiet life is again interrupted by the dog trapping service. This time, they manage to trap the poor mongrels and take them to a shelter.
The owner of the shelter notices that Hagen's paw is injured and sends the dog for treatment. While waiting for their turn in the treatment room, the mutts are watching a Tom and Jerry cartoon. The ginger dog notices a woman euthanizing a sick mongrel in a room next to them and puts it in a black bag.
Fortunately, Hagen escaped this fate. He was treated and put in a cage with other stray dogs. The staff distribute food bowls to the cages, but, unlike other dogs, Hagen does not even touch the food.
He can no longer trust people. The following day, some visitors come to the shelter to choose a pet. One of the visitors liked Hagen, but he becomes aggressive and tries to pounce on the girl as soon as she comes closer to the cage.
The owner of the shelter orders the employee to deal with the mad dog. At the same time, a concert begins at the music school where Lili performs. Daniel comes to the performance to support his daughter.
When an employee tries to put Hagen in a cage with other dogs, the dog breaks off his leash and attacks the man. He bites into the employee's neck, ruthlessly killing him. Hundreds of dogs break out of the cage and join Hagen, choosing him as the leader of their pack.
The owner of the shelter tries to stop the ginger dog, but he easily knocks her off her feet. The rest of the dogs run free after Hagen. A huge pack of stray dogs fills the streets, causing panic among the residents of the city.
Hungry and angry, they pounce on bystanders and take away their food. They also run into Lili's concert and surround the building from all sides. For their safety, people have to barricade themselves in the concert hall and wait for the police to help.
Lili is sure that Hagen is among the stray dogs, and she is going to go search for him. Peter tries to talk the girl out of this dangerous idea, but in the end helps her get outside and lends her his bike. Lili rides through the deserted streets, hoping to find her ginger friend and stop the attack.
Suddenly, the pack of stray dogs runs out of the alley and knocks the girl off her bike. They do not pounce on her but keep running instead, as if pursuing a specific goal. Having become the leader of the pack, Hagen decides to take revenge on all those who harmed him.
The first victim is the owner of the restaurant, who sold him to Szabolcs. The mongrels bite the man to death, leaving nothing but bloody pawprints on the windows of his restaurant. Lili is chasing the pack, so she ends up being the first to discover the murder scene.
She is detained by the police for violating the curfew, and she is put in a patrol car to be taken to safety. However, the girl manages to escape and arrives at the butcher’ shop. There she finds the corpse of a butcher torn apart, who was the next victim of Hagen's pack.
Lili gets sick from seeing the bloody mess, but she finds the strength to call Daniel. She tells her father that she is going to find Hagen before the cops find and shoot him. Police officers manage to surround and shoot a few dogs, but most of them manage to escape and continue their mission.
At the same time, Szabolcs is watching the news about the stray dogs who have gone berserk and act as an organized group. Hagen visits his tormentor and brings his friends along. The dog orders the mongrels to attack the man and, baring his teeth, watches as they tear him to pieces.
The white dog finds Lili and asks the girl to follow him because he could take her to Hagen. An animal control officer blocks their way and shoots the defenseless mongrel. Despite Lili's desperate pleas, the employee approaches the wounded dog and finishes him off.
The girl runs home to her father, where she finds the corpse of the landlord. Now she has no more doubts: Hagen's pack kills specific people and Daniel must be the last target. Lili rides to her father's work and warns him of the danger.
However, Daniel is also worried about the safety of his daughter, so he goes to the slaughterhouse to find some weapons. Meanwhile, the pack of dogs led by Hagen surround Lili in the street. The girl tries to talk to her pet, but he does not trust her after all that he had to go through.
He steps closer and closer to his owner and bares his teeth angrily, ready to pounce on the girl at any moment. Daniel runs out of the building with a blowtorch in his hands to drive the mongrels away and save his daughter. This makes the dogs even more aggressive, and they all start barking at Daniel.
Lili cries and tries to calm everyone down, but no one listens to her. Then she decides to play the rhapsody on the trumpet, which she once played for Hagen. Hearing a familiar melody, her pet finally calms down and lies down on the ground.
The pack follows his example and also lies down on the ground, listening to the calming music. Still in shock, Daniel realizes that the danger has passed and his daughter is safe. Having finished playing, the girl lies down on the ground opposite Hagen and his pack.
The dawn breaks and Daniel joins them.
