Following the events of the season two cliffhanger finale, season three of Defiance opens on the eve of an impending military siege upon the town, which has fallen on hard times following the collapse of its lucrative mines. Their fate uncertain, the townspeople face further threat with the surprise arrival of the mysterious and nearly extinct Omec, an alien race of warriors marked by the decades of subjugation they imposed upon the galaxy in the years preceding the Pale Wars.