During a trip, Elvira reads the Prince’s poetry book, which makes her dream about meeting the man of her dreams. Her widowed mother Rebekka has found a new romantic interest so the family is moving to their new home. There, Elvira and her sister Alma meet their step-father Otto and their new step-sister Agnes.
In a short private ceremony, Otto and Rebekka get married. Afterward Agnes gives Elvira a tour of the house. Elvira is really excited about all the pretty things and the beautiful forest outside, especially since she can see the royal castle in the distance.
During dinner, the family enjoys the wedding cake. Suddenly Otto has trouble breathing as he starts going through a heart attack. He coughs up blood on Agnes’ face and falls dead on the table.
The next day, Elvira tries comforting Agnes by sharing her own experience of losing her father. However Agnes snaps at her, saying Otto only married Rebekka for the money. Elvira rushes to tell her mother, who is currently learning the same information from the lawyers.
It turns out Rebekka married Otto for the money too, so they tricked each other when actually neither of them had anything. The lawyers explain that the land and cattle will be taken, and the only thing Rebekka receives is a few coins. After the lawyers leave, Rebekka collapses from the shock.
She thinks she’s too old to get another man, so Elvira says she’ll get married for the family. However Rebekka thinks Elvira is too ugly to get a proper man and Alma isn’t fertile yet, so she can’t get married either. A devastated Elvira returns to her room and stares at her face in the mirror for a while before popping a zit.
Sometime later a message arrives from the palace. The royal family will be having a ball soon and all noble maidens are invited because the prince will choose a bride. Agnes immediately signs up and so does Elvira, but when she fails to provide an important surname, Agnes introduces her as her stepsister.
The messenger writes down her name as “Elvira Von Stepsister” but she gets excited anyway and already dreams about being married to the prince. When Rebekka hears about the ball, she goes to a doctor to make Elvira prettier. He wants to remove the braces, fix her nose, and add eyelash extensions.
Rebekka promises to pay him double after the ball but Elvira can’t help noticing all the blood on the floor of the operating room. While Rebekka looks at a catalog of noses, the braces are removed without any issues. However the nose fix is quite painful because the doctor is using a chisel without any anesthesia and Elvira screams during the whole process.
Later Elvira joins a bunch of young maidens at a finishing school to learn social graces and she has to wear a support for her recovering nose. Three girls will be chosen by the teacher to show off to the Prince, but everyone still must make a good impression since the ball will be full of rich men who may choose them as wives. The first lesson is dancing and the teacher sends Elvira to the back of the group with all the ugly girls while Agnes is called to the front.
That night during dinner Elvira is served a very basic soup while everyone else gets to eat abundant dishes. Agnes wants to organize a funeral for her father and Rebekka tells her they must wait until Elvira gets a husband at the ball because of the money. A furious Agnes points out they’re wasting money on making Elvira pretty while Otto’s body is rotting, but Rebekka interrupts her to announce Alma and Elvira will get any dress of Agnes that she doesn’t wear anymore.
This causes Agnes to leave the room. When she checks on her father, bugs are eating his body and she screams. The next day lessons continue with different topics like the correct use of the fan, balancing books on their heads while going up and down the stairs, and how to courtsey.
At the end of the day the teacher hangs the list of chosen students that will pass to the next level and Elvira is surprised to see that another girl was crossed out to include her. This triggers more fantasies of her marrying the Prince. The following day the chosen group starts new lessons, which begin with more dancing.
The teacher calls Elvira to demonstrate first only to quickly interrupt her and call her wasted talent. It turns out Rebekka paid the teacher to make Elvira pass, otherwise she wouldn’t have been chosen. After humiliating Elvira in front of everyone, the teacher makes Agnes and two other girls come to the front to show how it’s done.
In the evening, Elvira tries some of Agen’s dresses but they’re too small for her. Rebekka orders her maids to find a way to make them fit. After they leave, Elvira looks at her bare body in the mirror and cries.
Then she gets a cinnamon roll she hid in her dresser and eats it. The next day all the girls have a one-on-one meeting with Madame Sophie, who tells Agnes that the Prince will love her. When it’s Elvira’s turn, she cries while explaining she feels hopeless and nobody will ever choose her.
Sophie says it’s not true and that she sees herself in Elvira. After making her take off the nose support, Sophie points out that Elvira is changing the outside to match the inside and calls her brave. She also gifts her a little something to remind her that it’s the inside that matters.
Later in the woods Elvira shows Alma the gift, which turns out to be a tapeworm egg. If she swallows it, she can eat as much as she wants and still lose weight because the worm eats what she eats. Once she becomes thin and beautiful, she can just take the antidote.
Alma thinks it’s a crazy idea but Elvira ignores her concerns and makes her promise she won’t tell anyone. Meanwhile Agnes meets with stable boy Isak, whom she’s been having a secret relationship with. She apologizes to him and swears she loves him, but she has no choice but to marry the prince.
In the forest, Elvira swallows the tapeworm egg. Suddenly a dead bird falls next to her and she hears some shouting. She goes to investigate and discovers three drunk men talking about finding a woman.
One of them is relieving himself and Elvira can’t help admiring his bare rear. When he turns around, their eyes meet and she’s shocked to realize this is Prince Julian. The other guys make naughty comments and Elvira runs away, only to hide and watch Julian hunt.
She cries while she has more fantasies about being with him. In the evening, Elvira comes home and hears some strange noises in the barn, so she goes to check. She’s shocked to discover Isak and Agnes getting dirty, so she rushes to tell her mother.
In the morning, Rebekka yells at Agnes while breaking things and calling her slurs. She throws her to the floor as she forbids her from seeing Isak again and breaks her necklace before announcing she’s now a servant. Then Isak is kicked out of the property without giving him time to change.
In her bedroom, Elvira continues to eat hidden pastries. Three months later the nose support is finally removed for good. Elvira now has a perfect face and a skinny body.
She likes looking out the window to watch Agnes work like a slave. Everyone calls her “Cinderella” now. During the next visit to the doctor, it’s time for the eyelash extensions.
Her head is strapped to the chair and a simple cream is put on her eyes to deal with the pain. A nurse keeps Elvira’s eyes open while the doctor sews the eyelashes, but the cream is not enough and Elvira screams in pain during the whole process. That night Alma wakes up and finds blood on her sheets, revealing she’s a woman now.
Elvira can’t sleep because of the thunderstorm, the pain, and the hunger. She’s so desperate that she leaves her room to find food even though her eyes are bandaged. Alma finds her in the corridor and Elvira pretends she’s going to the bathroom.
When she reaches the kitchen, Elvira hears a noise and fails to hide, but it’s just Agnes, who takes pity on her and feeds her. During the next dance lesson, it’s revealed that Sophie is secretly dating the teacher. Elvira is finally considered pretty enough to join the girls at the front demonstrating the dance.
In the evening, Agnes secretly brings Elvira some food while she’s taking a bath. When Elvira gets ready to brush, she’s horrified to discover she’s losing her hair. Moments later a man brings a beautiful gown that Rebekka says had a big cost.
While Agnes helps Elvira change, the man creepily grabs Agnes’ face and she responds by spitting in his face. The guy insults her and forcefully kisses her, but Agnes pushes him off and spits on the floor. Rebekka immediately orders her to clean it up.
Then the man notices that Elvira’s hair is falling, so he puts a wig on her head and says she’ll make them rich. In the middle of the night Elvira quietly leaves her room to get more food and hears her mother getting dirty with the guy. Meanwhile Agnes opens a chest and gets a dress she hid so she could attend the ball in secret.
When she tries to sneak out Elvira finds her and tries to steal the dress. They end up fighting and the dress is torn to shreds. They’re interrupted by Rebekka, who tells Elvira not to worry because Agnes can’t go to the ball without a dress.
She puts her daughter to bed and gives her some medicine to help her sleep. Agnes runs to cry to his father’s bedroom, which she’s filled with flowers to deal with the rotting stench. Nasty maggots are crawling on his entire body but silkworms are the ones to reach Agnes’ dress to fix it.
Suddenly Agnes wakes up when her dead mother appears before her. The lady says she left new shows in her daughter’s pockets and that her coach will turn back into a pumpkin at midnight. The next day Rebekka helps Elvira get ready with the wig.
At the party, each girl has a chance to introduce herself to the prince, who looks very bored. His friends make raunchy comments while a servant reads some information about each bachelorette. When it’s Elvira’s turn, Sophie tells the other lords how she trained her herself, but Julian still doesn’t look impressed.
Afterward it’s time for the dance and Elvira is chosen as the main dancer, which finally gets Julian’s attention. Then it’s time for the actual ball and many lords are looking forward to asking Elvira to dance, however Julian chooses her first. Elvira is filled with glee when Julian tells her she’s beautiful, but the dance is interrupted when Agnes arrives wearing a beautiful dress and a covered face.
The prince rushes to meet her and dances with her instead, so a heartbroken Elvira huffs out of the room. Suddenly she feels sick and runs to the changing room to throw up a bunch of tapeworm eggs. Rebekka soon comes after her and tells her to stop crying because there are more men to choose from.
When Elvira says she’s dying, Rebekka slaps her and forces her to go back. Elvira spends the rest of the night dancing with every man who asks her to, but she can’t stop staring at Agnes always dancing with Julian and her mother flirting with more lords, not to mention the dress seller is there too. When she starts seeing worms and maggots on the table and people’s necks, she realizes she’s getting dizzy and it's affecting her head.
Then the clock strikes twelve and Agnes announces she must leave before she runs away. Elvira watches with fury as the prince runs after her. When he comes back, he has Agnes’ shoe in his hand and says that he’ll marry the girl whose foot fits in it.
During the trip home, Elvira keeps yelling in frustration. Near the door, she finds the abandoned pumpkin. A furious Elvira grabs a knife and attacks Agnes, asking her to give her the shoe.
Agnes dodges the attack and defends herself, managing to disarm her stepsister. Elvira tries to choke her instead and a chase ensues. Rebekka hears all the screaming and stops Elvira just in time, but she never stops flirting with the man she’s brought home.
Agnes uses the chance to run away, dropping the other shoe on her way out. Afterward in her room, Elvira tries to put on the shoe but it doesn’t fit. Getting desperate, Elvira grabs the knife and starts making some cuts.
Her toes fall at the same time she does and her scream of pain gets Alma’s attention. While she wraps her scarf around her sister’s leg to slow the bleeding, Rebekka also hears the screaming and enters the room. She gives Elvira the sleeping medicine while explaining that she did the wrong foot.
A horrified Alma runs off while Rebekka finishes the job, leaving both of Elvira’s feet without toes. During the process, Elvira dreams of Julian putting the shoe on her foot and choosing her as his bride. The next morning Elvira wakes up in pain and falls off her bed while puking blood.
She can hear a servant announcing the arrival of the prince, so she crawls on the floor to leave her room. The stairs are a problem and she ends up rolling down the steps, bleeding on the floor where she lands. Agnes sees this but ignores her, choosing to go out to meet the prince instead.
Julian tries the shoe on Agnes and it fits perfectly, so she’s chosen as the next royal bride. The couple kisses while Elvira has a breakdown. Afterward Alma rescues her sister and forces her to drink the antidote, which forces the tapeworm to peek out of her mouth.
Alma grabs it to start pulling and pulling until the entirety of the very long worm is out of Elvira’s body. After killing the worm with a knife, Alam steals some of her mother’s jewelry. Rebekka sees her and ignores her to continue being naughty with a man.
Then Alma helps Elvira leave the house and get on a horse with her. Now both sisters can run away and leave their controlling mother behind.
