Ari Aster’s Midsommar is a disturbing daylight folk horror in which a grieving American student joins her boyfriend and friends on a trip to rural Sweden, only to encounter a pagan midsummer festival that grows increasingly sinister. Blending psychological dread, ritualistic folklore, and shocking violence, the film transforms sunlit beauty into an unrelenting nightmare of cult devotion and emotional collapse.

Från IMDB:
A couple travels to Northern Europe to visit a rural hometown's fabled Swedish 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.