Plot

Bailey lives with her brother Hunter and her father Bug, who raises them alone in a squat in northern Kent. Bug doesn't have much time to devote to them. Bailey looks for attention and adventure elsewhere.

Twelve-year-old Bailey, her father, Bug, and half-brother, Hunter, reside in a dilapidated building. One day, Bug tells Kayley, whom he has known for three months, that he is engaged to her and that they will get married the following Saturday. Shocked and irate, Bailey declares she will not be there and leaves.

Afterwards, Hunter tells Bailey that he and his companions belong to a vigilante organization. Curious, Bailey follows the boys as they storm into a house and threaten a man with a box cutter. Bailey flees into an empty field and spends the night there after the police are promptly called.

A mysterious man who goes by the name Bird greets her the following morning. She follows him to an apartment building where he looks for a woman who used to live there but is unable to locate her. After this, Bailey departs, but before Bug comes to take her home and grounds her for spending the entire night out, she spots Bird on the building's roof.

Bailey finds out that Bird was trying to find his mother, who lived in the apartment building and vanished when he was a young boy. Being kind to Bird, Bailey says her mother, Peyton, might be able to assist Bird because she used to reside in the complex.

While at Peyton's house, Bailey and Bird ask about the residents, but are cut off by her live-in boyfriend Skate's rudeness. Following a fight, Bailey records Skate, who then threatens to kill Peyton if Bailey shows the police the video. Peyton can nevertheless recall Bird's father's name. Hunter promises Bailey that he and his team will attack Skate to save her mother and her half-siblings, and Bailey forwards the video to Hunter.

Afterwards, Hunter asks Bailey to help him deliver a note to his girlfriend Moon, requesting that they flee to Scotland because her family disapproves of her newly found pregnancy. A crow assists Bailey in getting the note past Moon's family while she is traveling.

In order to prevent the incident, Bailey takes her half-siblings out for the day the following day while Hunter and his friends plot their attack. Bird comes back to assist Bailey and the children in getting to the beach, where he tries to find his father. Bird and Bailey discover his apartment, but the man there denies ever having a son. The man later retracts his denial and tells Bird that he was with Bird's mother and that they did have a boy, but that he left her soon after because he could not handle her unstable mental health. As the group makes their way home, Bailey comforts a teary Bird.

Not long after they get back, Skate tries to storm into their home. In the end, he attacks her after Peyton fails to stop him. Skate knocks Bailey out when she tries to stop him. Bird returns to the apartment and tries to protect Peyton as well, but Skate hits him with his head. Bailey sees Bird change into a creature with feathers, big wings, and eyes like birds while he is recuperating. When he battles Skate once more, he takes him outside, where Bird knocks him out, snatches his talons, and takes off with his body.

Bailey learns that Hunter has left the house the following morning. Devastated that Moon had not carried out his plans, she tells Bug, and the two rush to the train station, where they find him by himself. Hunter is reassured by Bug that he is too young to have children. After riding home, the three of them go to Bug and Kailey's wedding, where Bailey is feeling happier. Bird arrives unexpectedly at the reception and bids Bailey farewell with a hug. Bailey's eyes are shown to be bird-like as he departs, just like Bird's eyes were.