The sleepy Pacific Northwest town of Eureka is hiding a mysterious secret. The government has been relocating the world’s geniuses and their families to this rustic town for years where innovation and chaos have lived hand in hand. U.S. Marshal Jack Carter (Colin Ferguson) stumbles upon this odd town after wrecking his car and becoming stranded there. When the denizens of the town unleash an unknown scientific creation, Carter jumps in to try to restore order and consequently learns of one of the country’s best kept secrets. In the series finale, wormholes randomly materialize around Eureka as the Department of Defense is set to shut the town. The people of Eureka are being kidnapped and replaced by body-doubles one by one unless Allison, Fargo and Zane can figure out how to avoid capture and save their town. The Department of Justice arrives to investigate Grace, while Henry struggles with his conscience and Eureka is cut off from the world by a malfunctioning experiment that threatens to eradicate the town's populace. Jack and Allison's perfect honeymoon is interrupted when sabotage is discovered in Eureka. Elsewhere, Holly faces another hurdle to remain intact. While under the influence of a smart drug, Carter becomes a genius like everyone else in town and starts to change the laws of physics. Unfortunately, his condition soon endangers all of Eureka, including Allison's brother who is in town just to meet his new brother-in-law.