This is the story of a family struggling to deal with the accidental death of a teenage son. Calvin Jarrett (Donald Sutherland) and his wife Beth (Mary Tyler Moore) and their surviving teenage son Conrad (Timothy Hutton) live in a wealthy Chicago suburb. Some months before the time of the film, Conrad's older brother Buck drowned when the small boat he and Conrad were sailing capsized in a windstorm.
In the present we see Beth as cold, withdrawn from Conrad (Buck had been her favorite) and at times actively hostile to him and to her husband, too. Conrad, recently back home from three months in the hospital (including electro-convulsive shock therapy) after slitting his wrists, is between uneasy and agonized in his high-school and family world. Calvin remains emotionally open but is befuddled and often caught between his wife and his son, talking about things that don't matter.
Within that setting, the film tells the story of Conrad's attempts to deal with the guilt he feels after his brother's death. A series of psychotherapy sessions with Dr. Berger (Judd Hirsch) plays a crucial role. Seeing Dr. Berger also helps Cal understand some things, and when in a midnight confrontation he tells Beth of his sorrow that she has substantially changed for the worse, she proudly packs her bags and leaves. The film ends early the next morning, with Conrad and his father in an emotional embrace on the front steps of their home.