The trial of the "Upington 25" in South Africa in 1986 saw twenty-five men and women from a black township bordering the town of Upington tried for the murder of a local black policeman. Upington, a small white town located in the heart of Afrikaner nationalism, was besieged by the legal proceedings, which culminated in the conviction of all the defendants, fourteen sentenced to death, the assassination of the lawyer and human rights advocate Anton Lubowski, and the exile of the young lawyer Andrea Durbach who also represented the accused.

A COMMON PURPOSE follows Durbach, now director of the Australian Human Rights Council, as she returns to her homeland to meet with her clients from that landmark case. The story unfolds to reveal one of legal history's biggest cases on the death penalty.

The context, political, and legal events of the time are movingly recounted by the journalist John Carlin, many of the accused themselves, and Durbach. They tell a story of a struggle for justice in a country where injustice was entrenched in the law.

The film also examines the at-times distorted South African legal system, with an explosive and inspirational look at the subsequent Truth and Reconciliation Commission hearings.