Crotchety retired doctor Isak Borg travels from Stockholm to Lund, Sweden, with his pregnant and unhappy daughter-in-law, Marianne, in order to receive an honorary degree from his alma mater. Along the way, they encounter a series of hitchhikers, each of whom causes the elderly doctor to muse upon the pleasures and failures of his own life. These include the vivacious young Sara, a dead ringer for the doctor's own first love.

The defense and the prosecution have rested and the jury is filing into the jury room to decide if a young Spanish-American is guilty or innocent of murdering his father. What begins as an open and shut case soon becomes a mini-drama of each of the jurors' prejudices and preconceptions about the trial, the accused, and each other.

An ailing famous barrister agrees to defend a man in a sensational murder trial where his self-possessed wife's unconvincing testimony confuses him.