With Sara recuperating from her latest battle, Charlie starts to notice something might not be right with her. Still searching for the Loom, Constantine and Zari find themselves trapped in…

A scientist who is working on developing a source of clean energy is found murdered. The list of suspects leads Kiera on a journey that takes her to a precarious…

Re-captured by Lydecker after his helicopter crash, Zack is tortured in an effort to get him to reveal the whereabouts of the other X5 escapees. After a failed escape attempt,…

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.

Jack and Allison’s perfect honeymoon is interrupted when sabotage is discovered in Eureka. Elsewhere, Holly faces another hurdle to remain intact.

When Allison’s genius older brother comes to meet her new husband, Carter feels the pressure of not being smart enough to measure up.

Carter’s romantic surprise for Allison turns deadly when they’re trapped in a sinking marine lab with time and oxygen quickly running out.

Fargo is convinced that Holly is still inside of the Matrix computer, but the DOD is determined to wipe its hard drive clean — losing Dr. Marten forever.

Henry conducts a preparedness drill that winds up a disaster and Fargo faces a hard reality.

The crew moves forward after an ordeal and Warren’s visit adds to the pressure.

Beverly Barlowe resurfaces in Eureka seeking Carter’s help to free the Astraeus crew, and the rescue plan lands Carter in the crew’s virtual world.

The town huddles in a last attempt to locate the vanished Astraeus before it’s too late!

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.

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…

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.

Taggart achieves a medical breakthrough while Fargo invents a device that bridges the divide between computers and human brains.

A former resident returns to Eureka and creates mayhem which threatens Global Dynamics, prompting Stark to take action.

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

A sleeping weapons system is accidentally awakened by Fargo and Spencer. Henry tries to avert the pending catastrophe with the help of a retired, nonsensical scientist.

An unpredictable researcher accidentally unleashes a dangerous artifact which was previously hidden by Nathan Stark.

After hosting a movie party, Spencer is found the next day in the middle of a crop circle, claiming he was abducted by aliens; and then other people who attended…

Something starts to steal the townspeople’s memory…

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…

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.

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.

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.

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…

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…

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…

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…

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.

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

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…

The quaint town of geniuses is transformed into animated versions of themselves. Sheriff Carter and Allison Blake are secretly planning the perfect holiday surprise for their kids. But a mysterious…

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.

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

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

Eureka’s citizens face the return of people from the past; Global Dynamics tests a new device.

Love is in the air as Carter gets fed up with Grant’s pursuit of Allison, Zoe conceals her love and Henry courts Grace. But all the emotions may have to…