Dani, a young woman traumatized by a family tragedy, clings to her relationship with her indifferent boyfriend, Christian. Christian has been considering ending their relationship but, out of a sense of obligation, invites Dani to join him and his friends on a trip to a rural Swedish village. The group includes Christian's academic peers, Josh and Mark, as well as Pelle, an exchange student from that very village. They are travelling to attend a midsummer festival that is held only once every 90 years and promises to be a unique cultural experience, one that Christian hopes will bolster his anthropology thesis.

Upon arrival, the friends are struck by the idyllic landscape and welcomed with open arms by the villagers, who are adorned in white robes and exude an air of mystique and harmony. The community's traditions and rituals fascinate the visitors, with the promise of an authentic commune experience. However, what begins as a carefree summer holiday in a land of perpetual sunlight takes a sinister turn as the villagers invite their guests to partake in festivities that grow increasingly unnerving and viscerally disturbing, revealing that the pastoral paradise hides dark secrets.