Because of the actions of her irresponsible parents, a young girl is left alone on a decrepit country estate and survives inside her fantastic imagination.
Pre-teen Jeliza-Rose's parents are hopeless drug addicts. When pa, rocker Noah, finds ma's OD'd, he fears to be charged with homicide and takes Jeliza along to his ma's place, in a desolate country region. With Noah dead in his chair, the girl mentally transfers to a fantasy world she and her doll heads enter magically. Jeliza's adventures also star the crazy locals, notably Dell, and Dell's grown but intellectually disabled brother Dickens.
- Jeliza-Rose lives in Los Angeles with her junkie parents. Their only income is from her father's rock concerts and Jeliza-Rose only has a few belongings, mostly just broken toys and a hardcover copy of Alice's Adventures in Wonderland. When she isn't imagining things in her mind, she's busy looking after her parents and even filling their heroin needles for her father, who spends great amounts of time unconscious on the living room armchair. He has Jeliza-Rose believing that one day things will improve and that they'll run away together to live in Denmark. Jeliza-Rose's overweight chain-smoking mom has erratic mood swings, spends all day lying in bed eating a seemingly limitless supply of chocolate bars (and smacking Jeliza's hand and calling her a bitch if she tries to eat one) and she doesn't have the right mindset to be a parent, nor does the father.
One day Jeliza's mom chokes to death on a piece of chocolate after smoking too much. Not wanting the police to see the drug paraphernalia and give Jeliza to child services, her father helps Jeliza build her mom a shroud, and they then pack some things and get on a bus to Texas (Jeliza believes it's Denmark). Jeliza's father is obnoxious, vulgar and disgusting on the bus, purposely farting and telling the other passengers that it was Jeliza just to embarrass her. Eventually they arrive at an old shack vandalized by teenagers and literally falling apart. Rude phrases are spray-painted on the walls and evidence of squirrels living in the attic is seen by Jeliza, but she tries to make the most of her new "home" by showing it to her four imaginary friends, which happen to be the disembodied heads of vintage Barbie-dolls. Her favorite, named Mystique, becomes her closest companion for much of the film.
When Jeliza's father overdoses and dies that very night, Jeliza believes he is just unconscious. She plays elaborate imaginary games to pass the time, and although her father is visibly decomposing more and more every day, Jeliza tells herself that he isn't dead and retreats further away from reality. While playing under a tipped-over schoolbus by some train tracks, Jeliza meets Dell, an eccentric and mean-spirited lady who has a fear of bees and claims to have destroyed her family's beehives as a teenager. Jeliza at first believes Dell is a witch until she meets Dell's epileptic, intellectually-disabled brother Dickens and is determined to become part of the family. She begins snooping around and sees Dell having oral sex with a delivery boy to avoid paying for delivered groceries. Dickens tells Jeliza that doctors removed half his brain a long time ago to stop him from having seizures and he has a long scar on his head. Jeliza befriends him and joins him in a game where a pile of trash becomes a submarine in their minds and the train that passes by every afternoon becomes a "monster shark".
Eventually Jeliza can no longer tell fantasy from reality and when she accidentally drops Mystique down a rabbit-hole on Dell's property, she thinks that the other doll heads will turn against her. Dickens tries to rescue Mystique but is unable to. Eventually after living off of just a jar of peanut butter from her father, Jeliza faints and is rescued by Dell. Dell is a taxidermist and her unstable mind is revealed when, instead of trying to help Jeliza get to the police and report the death of the father, she preserves the father as a grotesque doll using his dried skin. She starts accepting Jeliza's presence but when Jeliza breaks down and cries, Dell shows no affection and seems to harbour some sort of grudge against Jeliza and her father. Jeliza lets Dell put all the old doll heads into the body of her father, sewing him shut and trapping them inside. Afterwards Dell, Dickens and Jeliza paint the whole house white, pray to God and then eat a bunch of Dell's home-made food. Jeliza begins to act less withdrawn, seeing the brother and sister as the closest thing to a family she's ever had.
One day while Dell is out in town and Jeliza and Dickens are alone in the old shack together, Jeliza puts makeup on him and begins to fall in love with him. Dickens doesn't understand that this is inappropriate, nor does Jeliza. Dickens recalls how as a little boy, his mother would tongue-kiss him and act in a perverse manner towards him, and about how his mother didn't really die from bee stings as Dell claims, she just fell down the stairs and died. Jeliza and Dickens kiss and then go off to play in the field after hearing a loud explosion noise. It turns out to be coming from a nearby mining quarry. Dickens reveals that he stole from the quarry an "atom bomb that will end the world and make Baby Jesus come alive like chemicals" (he shows this to Jeliza and it turns out he stole two packs of dynamite from the quarry but that in his mind it's an atom bomb). Jeliza tells him that if he shows her his bedroom, she'll let him keep her doll's arm. They also set a live squirrel free that Dell has caught and plans to kill. While in his bedroom, Dickens climbs on top of Jeliza and they tongue-kiss. Dickens' relationship with her nearly turns pedophilic, but then Dell catches them both.
It is revealed that Dell and Dickens' mother and father had relationships with their children and that Jeliza's father was a brother to Dell and Dickens, too. Dell and Jeliza's father had an incestuous relationship which was ended when the father ran away to marry his wife and play music. Jeliza was born later on and Dell is her aunt. Dickens is her uncle. Because of the abuse Dell suffered as a child and her devastation after Jeliza's father left her and her mother died, she snapped and became a recluse who has preserved her dead mother using taxidermy to avoid her grief over the dead.
Furious that Jeliza was about to kiss Dickens, thinking that she'll take him away from her, she threatens Jeliza and Jeliza accidentally squishes in the skull of her taxidermied grandmother. Dickens has a seizure and Jeliza runs away, crying hysterically until an explosion suddenly shatters the window to the shack. Realizing that Dickens used his dynamite to kill the "monster shark", Jeliza goes outside to investigate, finding that beyond her imagination the case is really that a mentally-disturbed man has caused a train crash, hurting tons of people. Still unsure of what's real and what isn't, she searches everywhere for Dickens but instead comes across an injured woman who kindly gives her a half of an orange she'd been eating and offers to help her. Jeliza sits down with the woman and stares off into space; meanwhile Dell can be seen in her nightgown wandering up and down the tracks through the flames and hurt people, calling her brother's name. The woman asks Jeliza if she's traveling alone and Jeliza tells the woman that fireflies are her friends and that she can speak to them in her mind. The woman just assumes that Jeliza is in shock since she has no knowledge of the girl's neglect or abuse. The film ends with an image of Jeliza's glazed-over, emotionally-distant eyes.