Several friends travel to Sweden to study as anthropologists a summer festival that is held every ninety years in the remote hometown of one of them. What begins as a dream vacation in a place where the sun never sets, gradually turns into a dark nightmare as the mysterious inhabitants invite them to participate in their disturbing festive activities.

Manchester, 1990. On a troubled estate, Alice is roped into babysitting for her neighbour, whose children claim to feed a nightly visitor from Hell. Between gangland tensions, local superstition and drug withdrawal, Alice must decide whether to abandon her new wards or stay the night.