An explorer visits the penal colony, where an officer demonstrates to him the Harrow, an instrument used to inflict capital punishment. The Harrow is an extraordinarily elegant instrument: the condemned man lies face-down on a Bed, while a complex system of needles inscribes the commandment he has broken (e.g. HONOR THY SUPERIORS) on his back. The needles pierce deeper and deeper until the prisoner dies. In the process of dying, however, the condemned man finally understands the nature of justice and his punishment. His face is transfigured, a sight edifying to all those who watch. The officer begins to demonstrate the Harrow on a prisoner condemned to die because he was sleeping on duty.

The machine was conceived and developed by the former Commandant. It soon becomes clear that the explorer does not approve of the death-machine and that he feels morally bound to express this disapproval to the new Commandant, who is already known to have serious questions about using the Harrow as a method of punishment. Suddenly, the officer removes the condemned man from the Bed and takes his place. Before doing so, he adjusts the machine to inscribe "BE JUST." The Harrow begins its grisly work on the officer's back, but malfunctions and goes to pieces--but not before the self-condemned officer has died.