The U.S.S. Enterprise visits the planet Angosia, which recently emerged victorious from a lengthy war and is now seeking membership in the Federation. During the visit, a violent prisoner in Angosia's penal colony escapes and is later captured with the help of the crew. The escapee, Roga Danar, is detained aboard the U.S.S. Enterprise while repairs to the damaged prison can be completed.

Although Troi has been warned that Danar is extremely dangerous, she is drawn to him when she senses that he is being tortured by nightmares. Meeting with the prisoner, she comes to believe that he is inherently non-violent, despite his reputation.

A check of Danar's records reveals that he is a military prisoner who served Angosia honorably in the recent war. He informs Troi that when he volunteered for service, his government conducted intense psychological and biochemical modifications on him and his fellow soldiers. When the men, programmed for violence in any situation threatening their survival, had difficulty readjusting to civilian life, they were exiled to Lunar V.

Confronted by Picard with Danar's story, Angosian Prime Minister Nayrok basically tells him to mind his own business and insists that the prisoner be returned. Picard reluctantly informs Danar that he will be sent back to prison via a police shuttle.

But during the transfer, Danar hijacks the shuttle and returns to Lunar V, where he leads an assault on the prison. Nayrok then sends an urgent message to Picard, informing him that hundreds of rioting prisoners are headed for the Angosian capitol.

In response to Nayrok's pleas, Picard leads an Away Team to Angosia, where he finds Nayrok and the members of his senate arming themselves against an attack. Just then, Danar and his comrades burst in, but knowing that the veterans will not kill unless their own lives are threatened, Picard vows that he and his crew will not fire upon the prisoners. Instead, Nayrok is urged to take steps to reprogram the soldiers and welcome them back into society — only then, Picard asserts upon leaving Nayrok and Danar, will the Federation reconsider the planet's application for membership.