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.
Carter 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.
Tiny makes an explosive reentry on the same day the Department of Defense demonstrates how little control Allison and Carter have over their personal lives by sending an auditor whose task it is to analyze their relationship. Elsewhere, Jo turns herself into a wedding planner extraordinaire for a reluctant Grace and Henry as Zane prolongs his departure, and Fargo must decide how he wants his relationship with Holly to progress. But none of it matters when it appears the gases Tiny brought back may be be the end of Eureka.moreless
Attacks in town may scuttle the Astraeus mission in the same week the final 20 will be named. Carter and Allison appeal the auditor's recommendation, but the proposed fix, a memory-reading gadget for the candidates' final interviews, may give them more details about each other than desired.
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.
The Astraeus participants make their farewells to their earthbound family and friends. Elsewhere, Carter and Jo investigate the person—or thing—which attacked the presidential convoy and if it is in any way related to the cosmic anomalies threatening Eureka.
As Carter and Blake prepare a Christmas surprise for the kids, a wave of energy sweeps over Eureka, transforming everyone into animated characters.