While vacationing on a remote island retreat, a family’s already fragile ties are tested when daughter Karin (Harriet Andersson) discovers her father has been using her schizophrenia for his own literary means. As she drifts in and out of lucidity, the father (Gunnar Björnstrand), along with Karin’s husband (Max von Sydow) and her younger brother (Lars Passgård) are unable to prevent Karin’s harrowing descent into the abyss of mental illness.