The fourth season of the fantasy series set in the quirky and seemingly perfect small town of Eureka, where the hidden work of America's brightest scientists can lead to innovation or utter chaos.
Dr. Grant, a former resident of the town, causes serious alarm with his unexpected return. His romantic interest in Allison Blake also causes significant friction with Sheriff Jack Carter.
As the Founder's Day festivities continue, Carter and the others must accustom themselves to the new time line and how Dr. Grant fits into it. Unfortunately, re-acclimatization needs to occur on a steep learning curve.
Dr. Isaac Parrish, the brilliant director of the Non-lethal Weapons Lab, is feeling a little undervalued these days. Then all his latent hostility goes viral, infecting everyone with such fury that no one is safe, especially Fargo.
As Eureka celebrates Space Week, Dr. Ramsey unveils his cutting edge invention that could allow colonization of Mars. Unfortunately, a slight malfunction may cause it to incinerate Eureka before the dream is realized. Equally bad is that Eureka's go-to guy for crisis intervention has just gone to Boston to visit his daughter at Harvard.
Claudia Donovan visits Eureka to see if Fargo's promises of wondrous devices are true, but she finds herself in the middle of a mystery suitable for Warehouse 13 when objects begin to appear randomly around the town and GD, and it must be solved before there are deadly consequences.
Carter's camping trip with Kevin becomes a little scarier than ghost stories by the camp fire when a malfunction with the AI at Global Dynamics may turn some of them deadly. Elsewhere, Henry thinks about telling Grace the truth.
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 be put on simmer when people in town start turning to stone.
The gang begins seeing visions of people from their pasts, while the town seems to be collapsing around them. Meanwhile, Dr. Grant gets involved with a mysterious faction.
Dr. Grant attempts to return to 1947 but when Carter intrudes, they both wind up stuck in the past under the threat of altering present-day Eureka once again.
Carter can't get into the Christmas spirit especially with the town surrounded by a force-field. Fargo organizes the GD holiday party, and Allison is full of holiday cheer.
Zane pesters Jo for details she does not want to reveal. Carter problem-solves at Andy and S.A.R.A.H.'s wedding. Elsewhere, Zane's actions make him and Fargo unexpectedly airborne.
Carter's duties expand to babysitting when Allison attends a medical conference, and Fargo finds his groove when a certain song is played. Meanwhile, a rocket scientist appears at Café Diem.
Jo receives a technical boost to her crime-fighting ability with lenses that predict security breaches. Allison's headaches won't go away so Carter plans a vacation. Fargo, meanwhile, deals with an onslaught of volunteers when he announces a space mission with room for civilians.
Jack deals with a bank robbery which may relate to the sudden gravity issues besetting the citizens of Eureka. Meanwhile, Fargo's rivalry with Isaac Parrish is boosted when he learns Holly and Parrish went on a date.
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. SYFY has this & "Of Mites and Men" Listed as episode 16 and does not have #17 "Clash of the Titans Listed"
Global Dynamics deals with two threats—a visit from Senator Wen and robotic bugs that can consume everything—it's unclear which is the bigger one. Meanwhile, Allison refuses to acknowledge any deficit with which the implants may have left her. SYFY has this & "Omega Girls" Listed as episode 16 and does not have #17 "Clash of the Titans Listed"
The Eureka atmosphere becomes toxic when Department of Defense auditor comes to assess the team's relationships.
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 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 kaleidoscopic wave of color crashes over Eureka, leaving the entire town and its inhabitants animated.