An accident leads a U.S. Marshal and a teenage girl (who later is revealed to be his daughter) to a peculiar town populated by scientists and their families where 10-year-old boys are in 11th grade, the local diner doesn't believe in menus, and E=MC² was just the beginning. Just as the Marshal starts to get settled into the swing of things, a local scientist develops a bomb that seems to appear anywhere and eats all the matter around it.

The citizens of Eureka attend the funeral of Susan Perkins, only to find out that she is in fact alive. Meanwhile the Sheriff moves into an underground bunker that is actually a 'smart house' controlled by a computer dubbed 'S.A.R.A.H., and begins to investigate a 'ghost' that has been appearing in town.

Carter investigates an unusual car accident. Meanwhile, Stark, under the stress of completing a project on time, pressures two research teams to produce results.

Strange behavior exhibited by the townspeople is investigated by Carter,who has to solve the mystery before Stark makes a decision that could affect the world.

Ambition trumps common sense when Stark is given a chance to try out the Top-secret artifact. Once it's tested, Eureka warps into the future and ends up in 2010, where the town is different.

Taggart's theory is that solar flares caused by the eclipse, or the 'Phoenix Effect', are to blame when people start to spontaneously combust. When Carter discovers that a blast of radiation from the artifact had penetrated the wall of the chamber and is actually to blame for the spontaneous combustion, it becomes a race against time to save the other two people exposed - Nathan and Kevin!

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.

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?

The search is one for an escaped drone as Eva Thorne arrives to assist the clean up of damages which Global Dynamics has caused.

The Eureka mayoral race is overshadowed by the sudden arrival of a second sun, forcing Carter, Allison and Zane to investigate it more closely.

Jo displays atypical behavior after a DNA scan malfunctions, unfortunately it's while she's interim sheriff because Carter is undergoing a 48-hour DOD recertification test.

Tess has a job offer from Australia, Zoe is prepared to leave for Harvard and Carter has a magnetic disturbance above Eureka to contend with, in the third season finale.

It's Founder's Day in Eureka and everyone is in the spirit of the celebration until Jack, Allison, Henry, Jo and Fargo are transported back to 1947 where they meet some familiar faces along the way. Will they be able to get back to 2010 or will they be stuck forever in 1947 where Eureka is not a town, but an Army base.

When Grant and Carter become stranded, they must race back in time to save Eureka.

When Zoe comes home for a visit, Jo faces an angry woman who doesn't accept her fumbling explanations about Zane. This all fades to background noise, however, when they find everyone in Eureka unconscious and must find a way to work together so they can revive the town and beat Beverly before she gets hold of valuable data.

The Astraeus candidates go through their final interviews while Carter and Allison appeal their relationship audit.

When an explosion in the Astraeus lab accidentally sends Andy to Titan the team must devise a plan to save him before it's too late! Eureka

In the season finale - It's chaos in Eureka when an energy beam rips through main street but the Astraeus launch must go on...with or without Eureka intact.

The Astraeus crew returns to Eureka four years later and must adapt to a myriad of changes, including a more oppressive version of Deputy Andy.

Wormholes randomly materialize around Eureka as the Department of Defense is set to shut the town.