The premise of the chamber drama that is "Hoysommer" is the changing relationship between a lonely temporary keeper of a remote lighthouse and an attractive but troubled young woman who lands up, unconscious, in a dingy near his buildings.

The landscape of the lighthouse area, the waves and rocks, is ,typical for a Scandinavian film ,also a part of the story but the main interest is in the way the characters interact. The woman at first is wary of the man and wants to leave but is restrained by his concern for her health (she has tried to kill herself) Then when he wants to report her after radio inquiries as to her whereabouts, he is persuaded by her repeated entreaties to let her stay on just another night, until they land up falling in love.

A few minor characters including the woman's elderly husband appear at various points but the drama of what will happen between the man and the woman sustains itself in a satisfying way up until the conclusion.