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.

It's Founder's Day in Eureka and everyone is in the spirit of the celebration until Jack is transported back to 1947 where he meets 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 a camp.

When the 5 get back to their time, things are changed everywhere. As the Henry tries to fix the machine that transported them in the first place, Dr. Grant is making himself comfortable as he can. Jack is still trying to wrap his mind at the fact that he asked Tess something that she says yes to and the fact that the group's positions changed.

Fargo must face some primitive and childish emotions in himself when he must deal with Dr. Isaac Parrish, the brilliant director of the Non-lethal Weapons Lab whose superior social skills and condescending attitude may cause Fargo to take a risk to prove himself worthy that can only have a Fargo-like outcome.

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.

Just as Carter and Allison seem to get everything right, people from their pasts appear to complicate things. Elsewhere, GD's new project perks the interest of Beverly Barlowe.

When an important GD project disappears, Carter, Jo, Fargo and Allison must put aside their differences to find it before it causes damage. Unfortunately, Trevor Grant's conveniently timed absence makes him a suspect, and the proverbial noose around his neck only tightens when they discover evidence that connects him to Beverly Barlowe.

Carter's plans to visit family for the holidays are thwarted when the town is trapped by a electromagnetic shield.

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 duties 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 boosted when he learns Holly and Parrish went on a date.

Jo and Zoe return to Eureka only to find the entire town incapacitated and communications cut off.

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.

Jo has wedding ideas for Henry and Grace; the Department of Defense sends a relationship auditor to assess Carter and Allison; Tiny's return threatens the town with poisonous gases.

When the "Astraeus" mission is put in jeopardy by strange things, Jack starts to have Deje Vu with the things that are happening around Eureka. The final lists for the chosen 20 comes out and not everyone is happy about it.

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.

In the Season 4 finale, Carter and Jo respond to a mysterious attack on the presidential convoy; good-byes are exchanged before the Astraeus mission is launched; and cosmic anomalies threaten Eureka.