Fargo accidentally triggers a prototype for a personal force field, which goes out of control, forcing Carter to enlist Stark's help.

Dr. Whiticus creates an incredible "weather machine" intended to reverse the effects of global warming which instead stirs unexpected results.

Carter suffers a blow to the head, and after arguing with Zoe, he suddenly finds himself in a parallel Eureka, where the residents seem to be mysteriously vanishing.

Falling space debris threatens Eureka residents and Carter turns to high school science fair participants to solve the problem. Specifically, he taps a student science project created to harness the sun's energy. Also, Zoe gets an eco-friendly automobile.

One of the Global Dynamics tanker trucks spills, potentially causing a change in everyone's sleep habits... In the course of the episode, we come to learn that Global Dynamics has developed a technology that enables them to distill six months of the town waste and by-products into one truck, an amount that would normally fill Lake Erie.

Fargo's grandfather awakens after 50 years in cryogenic suspension and accuses his rival of putting him there and stealing his work.

As an experiment that will recreate the first moment of the origins of the universe, the Big Bang, goes terribly awry, the town’s geniuses turn into morons, leaving the fate of Eureka in the hand of Jack Carter and an antisocial young ubergenius.

An abandoned research project on invisibility returns to haunt Eureka. Carter and Zoé become tangled in a web of strange occurrences that lead to Carter’s disappearance and the possibility that he might never reappear.

Sudden muteness, human bioluminescence and faucets running blood cause many of Eureka’s citizens to believe that they are the victims of a biblical plague.

Sheriff Jack Carter becomes absolutely irresistible to every woman in Eureka. But if he doesn't get his mojo under control, they might just eat him alive.

Beverly Barlow returns to town just as a parasitic bacterium threatens to destroy Eureka, by turning everything to gold and then into rust --- people included.

Nathan Stark and Jack Carter must put aside their rivalry to stop a deadly bacteria from destroying the town and killing Allison’s son. But can Carter ignore Stark’s crimes, as well?