Karin (Harriet Andersson) hopes to recover from her recent stay at a mental hospital by spending the summer at her family's cottage on a tiny island. Her husband, Martin (Max von Sydow), cares for her but is frustrated by her physical withdrawal. Her younger bother, Minus (Lars Passgård), is confused by Karin's vulnerability and his own budding sexuality. Their father, David (Gunnar Björnstrand), cannot overcome his haughty remoteness. Beset by visions, Karin descends further into madness.