"In the Penal Colony" opens with an officer showing an explorer a remarkable apparatus, a capital punishment machine The explorer has been invited to witness an execution due to take place in a dry and desolate valley on a remote island. Four characters are present: the officer, the explorer, the condemned man, and a soldier. Also mentioned is a fifth character, a Commandant, who is responsible for inviting the explorer to witness the execution.

Although he has accepted the invitation, the explorer is unenthusiastic about the apparatus and initially indifferent to the plight of the condemned man. The officer busies himself making last minute adjustments to the machine. He is dressed in a heavy uniform, which the explorer considers quite unsuitable for the tropical climate. The officer agrees but explains that the uniform reminds him of home. He is a serving officer in a colonial military...