A couple travels to Sweden to visit a rural hometown’s fabled mid-summer festival. What begins as an idyllic retreat quickly devolves into an increasingly violent and bizarre competition at the hands of a pagan cult.
A college student named Dani (Florence Pugh) experiences a horrible tragedy when her sister kills herself and their parents. She receives consolation from her distant boyfriend Christian (Jack Reynor). A while later, they are invited to join Christian’s friends for a trip to Sweden where they will travel to the commune where Christian’s friend Pelle grew up. The basis of the trip is a midsommar celebration that supposedly occurs every 90 years.
While there, the group meets Pelle’s brother Ingemar, as well as an English couple, Simon and Connie. Although things seem to be nothing more than a cultural learning experience, it becomes horrifying when they witness two elders jump to their deaths for a ritual. Simon and Connie try leaving after this, but they instead disappear, and the villagers make it seem like they left safely. Christian’s friends Josh and Mark are also killed after the former takes pictures of the commune’s book of paintings that provide a basis for their rituals, while the latter urinated on an ancestral tree.
Dani slowly adjusts to the commune’s customs, and is later crowned May Queen after winning a maypole dancing competition. However, she witnesses Christian taking the virginity of a village girl named Maja. Dani breaks down at the sight of it, but the other women in the village mimic her cries, appearing sympathetic to her.
At the end of the celebration, Dani must choose a sacrifice for the final ritual. She chooses Christian, who is drugged and paralyzed before being put into a bear suit, and he is later burned to death alongside Ingemar and the corpses of his friends. Dani has all but lost her sanity, and she smiles as her boyfriend burns inside a teepee.
College student Dani Ardor suffers from severe emotional trauma after her bipolar sister commits a murder-suicide with their parents. As a result, Dani’s precarious relationship with her already emotionally-distant boyfriend, Christian Hughes — an anthropology graduate student — is adversely affected.
The following summer, Dani attends a party with Christian, where she learns that he, along with fellow graduate students Mark and Josh, had been invited by their Swedish friend Pelle to attend a midsummer celebration that occurs once every ninety years at Pelle’s ancestral commune, the Hårga, in Hälsingland. After Dani finds out about the trip two weeks before the flight, Christian awkwardly invites her to join them.
The group arrives at the commune where they take a psilocybin concoction together at the request of the villagers, resulting in Dani having a bad trip due to unstable hallucinations of her dead sister. Later, they meet Simon and Connie, an English couple also invited to attend by Pelle’s brother, Ingemar.
Tensions rise after Pelle brings the six of them to witness an ättestupa ritual in which two of the commune elders commit senicide by leaping from a clifftop. When the male elder fails to die as a result of the fall, several members crush his skull with a mallet. Though Siv, a female elder, insists the ritual is perfectly normal according to Hårga’s cultural beliefs regarding death, the four students find the ritual disturbing, especially Dani, who wishes to leave immediately. However, they decide to stay, both at the behest of Pelle and because the Hårga are the subject of Josh’s thesis. The following morning, Connie and Simon disappear, but the group is assured they were taken to the train station.
Christian decides to copy Josh’s thesis, setting a rift between the two. Josh attempts to glean more information from an elder on the commune’s ancient runic practices, which are based on paintings made by a deformed member birthed of incest, whom they consider an oracle. After Mark unwittingly urinates on the community’s ancestral tree, he is lured away by a female member. That night, Josh sneaks into a temple to photograph their sacred runic text and is hit over the head with an ax by a partially nude man wearing Mark’s skinned face and dragged out of the building.
The next day, Dani participates in a maypole dancing competition, and upon winning, is crowned the “May Queen,” an esteemed title in the cult. At the same time, Christian is drugged and groomed to participate in a ritual in which he impregnates commune member Maja while female elders watch. After discovering Christian having sex with Maja, a horrified Dani has a panic attack, and several of the Hårga women wail with her. Shortly after the ritual, a disoriented Christian discovers Josh’s leg partially buried and Simon’s body, ritually dismembered as a blood eagle. Christian is found and paralyzed by an elder with the aid of an unknown drug.
The cult explains that, at the conclusion of the ritual, nine human sacrifices must be offered: four outsiders (Josh, Mark, Simon, and Connie), four cult members (two unidentified elders and two living volunteers), and a final living victim. As the May Queen, Dani has to choose the final victim: either an outsider or a lottery-selected villager. Bitter and heartbroken, Dani chooses to sacrifice Christian.
Christian is stuffed into a disemboweled bear and placed in a designated temple, alongside the still-living Ingemar, a second villager, and the ritualistically-prepared corpses of Josh, Mark, Simon, Connie, and the two elders. The temple is burned in an effort to purge the cult’s evil. As the cult celebrates the completion of their ritual, Dani sobs in horror, but gradually begins to smile.
The film opens with a mural of a bizarre, eerie ritual taking place. We then see images of dark, snowy forests with the sound of old folk singing playing in the background.
College student Dani Ardor (Florence Pugh) calls her parents but is sent to voicemail. She expresses concern over her bipolar sister Terri (Klauda Csanyi), who left her a cryptic message recently. Dani then calls her boyfriend Christian Hughes (Jack Reynor), who is hanging out with his buddies Josh (William Jackson Harper), Mark (Will Poulter), and Pelle (Vilhelm Blomgren). Christian assures Dani that this is just another one of Terri’s episodes, but he adds that Dani only feeds into Terri’s antics. After he hangs up, she gets a call from an unknown number. Josh and Mark think Christian should just end it with Dani since it’s clear he’s wanted out of the relationship for a while, and as they are planning an upcoming trip to Sweden, Pelle suggests they will meet lots of other women. Dani calls Christian again and is wailing hysterically. We then see authorities going into Dani’s parents’ home, where Terri has flooded the house with carbon monoxide, killing her parents before stuffing the tube into her mouth and taping it there. Christian goes to Dani’s apartment to console her.
A while later, Dani tries to contain her grief. She hangs out with Christian and his friends and learns about their trip to Sweden to a midsommar celebration in the Harga, a village where Pelle grew up. The celebration occurs every 90 years and lasts about nine days. Josh, in particular, is interested since he wants to write about the experience for his anthropology dissertation. Christian invites Dani to be nice, and although she accepts, Christian thinks she doesn’t want to go since she’s still reeling from the murder-suicide. However, Dani is more upset that Christian is only now telling her about the trip, which they are set to leave for within two weeks.
Dani and Christian go to hang out with his friends. While he steps out of the room, Pelle talks to Dani about the midsommar celebration, and their tradition of choosing a May Queen at the end of the celebration. Pelle also tries to console Dani over her loss, stating that his parents had also passed away, but the mere mention of it triggers her, and she goes to the bathroom to cry.
Dani joins Christian and his friends for the trip. They drive out to the Harga and meet Pelle’s brother Ingemar (Hampus Hallberg), plus an English couple named Simon (Archie Madekewe) and Connie (Ellora Torchia). The group takes magic mushrooms, but Ingemar offers Dani a special tea since it has a better taste. She agrees to it and initially enjoys the trip until Pelle says that the group is like his family. The word gets to Dani, and she goes to take a walk. She starts to experience a bad trip, and gets paranoid when another high group of people she comes across starts laughing in her direction. Dani goes to hide in a shed but is mortified by what appears to be Terri behind her. She then runs into the woods, where the trees appear to morph around her before she passes out. She briefly dreams about Terri and their parents.
Dani wakes up next to Christian six hours later. They join their friends in going back toward the village to meet the rest of the Harga community. Josh inquires about the many cultural aspects of the festival and the community, but when he asks about a mysterious golden teepee in the distance, he doesn’t get a direct answer. A girl named Maja (Isabelle Grill) shows interest in Christian by playfully kicking him as he sits in a circle.
Pelle later gifts Dani with a drawing of herself for her birthday. She mentions that Christian forgot their birthday, but he later gives her a slice of cake to make up for it. When asked how long they have been together, Christian thinks it has just been over three years, but Dani corrects him and says they have been together for four years. Pelle then brings his friends to the place where they will be sleeping.
The following day, the group joins the community for a feast. Two of the eldest villagers, Ylva (Katarina Weidhagen) and The Laborer (Lars Varinger), are the guests of honor, as they practice a breathing exercise before the whole community follows them to the edge of a cliff. The elders cut their hands as they walk by the edge. The newcomers watch in horror as Ylva drops herself off the cliff and lands facefirst onto a rock, leaving them to witness her gruesome faceless skull. The Laborer leaps off as well, but he only shatters his leg. He moans in agony, and the villagers mimic the sounds of his moaning. Three of the villagers proceed to smash his head with a sledgehammer. Simon and Connie express their absolute horror, while Dani goes back to her room. An elder villager woman, Siv (Gunnel Fred), explains to the group that this is a natural part of their ritual, as the two elders reached what they felt was the end of their life cycle, and prolonging it further would have been bad. Pelle goes to comfort Dani, thinking that her distress is linked more to her recent tragedy than it is to what she just witnessed. He attempts to console Dani, but she thinks him getting close to her is inappropriate since Christian could come in. Pelle then questions how much Christian really means to Dani, based on how he is around her.
Dani later has a nightmare that Christian and his friends are leaving without her. They drive away in the middle of the night as she watches them go, and she is plagued by haunting imagery of her dead family and the corpses of the two elders.
After what they saw, Simon and Connie plan to leave, but when Connie is ready to go, she is told that Simon went off with another villager to the train that would take them home. Connie is angered that Simon would leave without her, and she proceeds to walk off on her own. Meanwhile, Christian tells Josh he also wants to do his thesis on the Harga, but Josh is not happy about that. He argues that Christian can never just do his own thing instead of picking off what Josh is doing. Christian offers to ask the elders if they are allowed to collaborate on the project. Josh later learns that the village’s ritualistic practices are based on paintings made by a member named Ruben (Levente Puczko-Smith), a deformed boy who was the product of incest but is viewed as some kind of seer. Josh asks to take pictures of Ruben’s drawings, but he is forbidden.
The elders’ bodies are buried in the middle of the village. Their ashes are spread across an ancestral tree, which Mark pisses on. He is scolded by Ulf (Henrik Norlen), who actually breaks down sobbing at the act. Mark is then told the significance of the tree, but he has a callous reaction over it. Elsewhere, Christian and Josh are told that they are allowed to collaborate on their thesis, on the condition that they omit the actual names and location of the Harga. The two agree. Christian also asks about the village’s mating rituals, inquiring as to whether incest was typical there, and he is told that incest isn’t necessarily frowned upon, but outsiders are usually brought in to procreate with the villagers. A feast is then held, where Mark notices Ulf is staring daggers in his direction. Dani also overhears that Connie was taken to the station by one of the villagers. Mark is then taken away by a female villager, and the others never see him again.
Later that night, Josh sneaks into the room where Ruben’s book of paintings is kept. He is interrupted by who he thinks is Mark before he gets bludgeoned over the head. We then see that the figure is actually a villager wearing Mark’s face. Josh is then dragged away.
The next morning, Dani, Christian, and Pelle are told that Ruben’s book has gone missing, and Josh and Mark disappearing looks suspicious. Afterwards, Dani joins the women in the village in a competition where they dance around a maypole before each woman is eliminated. After taking a drug, Dani finds herself being able to speak in Swedish with the other women. Dani is the last one standing, and she is crowned the May Queen. At the same time, Christian is given a drink that induces a trip. He is lured and taken to take Maja’s virginity. He has sex with her while the other elder females stand nude around them and mimic Maja’s moaning. After Dani is crowned May Queen, she watches Christian having sex with Maja through a hole in the door, which causes Dani to have a breakdown. She goes to cry, and the other women join her, sympathetically crying loudly with her. After climaxing, a mortified Christian runs out to try and find Dani, but he ends up discovering Josh’s leg buried in the dirt, as well as Simon’s mutilated corpse being used as a blood eagle. Moments later, he is found and knocked out when a villager blows powder in his face.
The end of the ritual draws near, and the elders bring the drugged Christian, along with Ingemar, before Dani, as she is supposed to choose someone for a sacrifice. As per tradition, nine people are to be sacrificed. This includes the two elders, four outsiders, two living volunteers, and one chosen by Dani. After all that she has gone through, she picks Christian.
The men in the village take a fully grown bear and disembowel it so they can place Christian inside the bear’s corpse. They bring him, Ingemar, and the corpses of Simon, Connie, Josh, and Mark to the golden teepee, which is then set on fire. Unable to move or speak, Christian succumbs to his fate while only being able to wheeze in pain, while Ingemar screams in terror. The villagers mimic the screams, while Dani appears to breakdown from what is happening again. However, as she continues to watch the teepee go up in flames, and hears the unified wailing of the villagers, a demented smile begins to form on her face.