Season 3 kicks off with a hunt for an escaped drone while Samantha Thorne arrives on the scene to oversee the clean-up of damages caused by Global Dynamics. (TV Guide)
A scientist somehow vanishes from a sealed biosphere, prompting Carter and Allison to investigate. Meanwhile, the "Fixer" attempts to make Eureka's efforts more profitable. (TV Guide)
The town's annual dog show segues into a canine malfunction; Zoe worries about the impact of the accelerated physics program on her life; earthquakes affect Allison's wedding plans. (TV Guide)
The emergence of a superhero makes Carter's job more difficult; Thorne's subterranean search for a secret beneath Eureka imperils Zoe and her friends. (TV Guide)
The arrival of a second sun over Eureka upstages the town's mayoral race and forces Carter, Allison and Zane to investigate the fiery threat. (TV Guide)
Following his termination as sheriff, Carter interviews for a job with the Department of Homeland Security. Deputy Lupo resigns when she learns the new sheriff is a very personable robot. (TV Guide)
While Carter undergoes a grueling test for his recertification, Jo takes over as Sheriff. But a zap from the town's new DNA-monitoring security system leaves her not entirely herself.
A strange structure comprised of electronics and scrap metal is assembled in a field by Eureka's teenagers, who appear to have been manipulated while they were sleeping. (TV Guide)
When a prototype ship from Henry's past returns, he encounters a computer-created copy of his late girlfriend, Kim. Meanwhile, Eureka experiences strange electrical anomalies.
A sonic cleaning at Global Dynamics coincides with a phenomenon that causes Eureka's citizens to develop a communal form of Alzheimer's. Meanwhile, Allison goes into labor in the third-season finale. (TV Guide)
Taggart returns to town with a valuable new research project: a massive core of ice that may hold secrets to Earth's past ... and an icy threat to the entire town.
Tess receives a job offer in Australia, Zoe is set to leave for Harvard, and Carter must contend with a magnetic disturbance that's floating above Eureka. (TV Guide)
