Founder's Day Carter and friends are mysteriously transported to a dangerous military installation. Getting home seems impossible, but whether they escape or not, their journey will have life-altering repercussions.
A New World Carter and his fellow travelers begin to realize the startling implications of their return to Eureka - and of Dr. Grant's unnerving appearance in their midst.
All The Rage Dr. Isaac Parrish is an underappreciated scientist whose hostility appears to have gone viral. Blind rage is infecting everyone at Global Dynamics with potentially catastrophic results - especially for Fargo.
The Story Of O2 Allison struggles to relate to her son and deals with inadvertent mayhem during Eureka's Space Week festival, while Carter wonders if the Zoe he is about to visit at Harvard will be the daughter he remembers.
Crossing Over Carter enlists the help of Warehouse 13's Claudia Donovan when strange objects materialize in Eureka that could erase the town.
Momstrosity Carter goes camping with Kevin, and Henry wants to come clean with Grace while a peculiar relationship threatens Eureka.
Stoned Tensions between Carter and Grant over Allison peak, Henry woos his own wife and Zoe deals with a secret love as something begins turning townsfolk into stone.
The Ex-Files People from their pasts haunt Carter and the gang while unknown forces attack Eureka.
I'll Be Seeing You A stolen Global Dynamics project brings Carter, Allison, Jo and Fargo together, and Grant's disappearance turns him into a suspect in the theft. Carter and Jo find evidence linking Grant to Beverly Barlowe before a catastrophe strikes.
O Little Town As the Global Dynamics employees celebrate the season at the company holiday party, staff member Dr. Noah Drummer nearly absconds with a volatile experiment. The halls get seriously decked when Dr. Drummer's unstable hydrogen crystal starts to grow at a frightening rate. Carter and Henry attempt to deal with the potentially explosive crystal, but before long the true scope of the problem is revealed, and it will take more than tinsel and carolers to save Christmas and Eureka.
Liftoff Carter lands in an awkward situation after S.A.R.A.H. and Andy's nuptials hit a snag; Zane keeps harassing Jo for details; an unscheduled launch presents trouble for the gang.
Reprise A rocket scientist arrives at Cafe Diem; a song prompts Fargo to display some fighting moves; Carter is tasked with minding Allison's kids while she leaves town for a medical conference.
Glimpse Applicants swarm Fargo after he solicits volunteers for a space mission; persistent headaches plague Allison; Carter plans a getaway; Lupo is fitted with special lenses that help predict possible security threats and calamities.
Up In The Air Carter must solve a bank robbery or the town may float away.
Omega Girls Lupo tries to explain to Zoe what happened with Zane, but the ladies find a bigger problem in town.
Of Mites And Men Robotic bugs plague Global Dynamics, and Carter talks to Allison about her mental state.
Clash Of The Titans 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.
This One Time At Space Camp... Sen. Wen conducts final evaluations of the Astraeus candidates, and the aspiring crew mates are fitted with memory-reading devices that expose their inner motives for wanting to join the mission; Carter and Allison wear the memory-reading devices as part of their appeal to reverse the ruling on their relationship; bizarre attacks occur around town that could threaten the Astraeus mission.
One Small Step Carter and Taggart probe the mystery of a melted cow; Jo questions what she wants from life; a malfunction strands Deputy Andy on Titan; Carter and Allison contemplate what's next for their relationship.
One Giant Leap 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.