The search is one for an escaped drone as Eva Thorne arrives to assist the clean up of damages which Global Dynamics has caused.

Carter and Allison investigate when a scientist mysteriously disappears from a sealed biosphere. Meanwhile, the "Fixer" tries to make Eureka's efforts more profitable.

Eureka's annual dog show is underway and is like none other. Meanwhile, Sheriff Carter experiences an earthquake; Zoe debates quitting the accelerated physics program; and Allison starts the process of fitting her wedding dress.

A search for a mummy ensues after a famed archaeologist opens the tomb of an Egyptian queen at Global Dynamics.

Carter's job is made more difficult when a super hero emerges. Meanwhile, Zoe and her friends are imperiled when Thorne makes a subterranean search beneath Eureka.

The Eureka mayoral race is overshadowed by the sudden arrival of a second sun, forcing Carter, Allison and Zane to investigate it more closely.

Trust issues are produced by a scientific find, along with sinister results. Zoe's life is in jeopardy, and Eva Thorne knows what has caused the predicament.

Carter interviews for a job with the Department of Homeland Security, after being terminated as the sheriff. Deputy Lupo decides to resign after discovering that a very personable robot is the new sheriff.

Jo displays atypical behavior after a DNA scan malfunctions, unfortunately it's while she's interim sheriff because Carter is undergoing a 48-hour DOD recertification test.

Dr. Tess Fontana reopens Section 5, causing objects to become ambulatory , possibly due to poltergeists.

Carter finds himself chasing down creation of blob-ical like proportions when a series of escalating pranks turn deadly. Elsewhere, long-term rivals from Area 51 come to Eureka for a bowling tournament.

Eureka's teenagers who appear to have been manipulated while asleep, gathered in a field where they assembled a strange structure comprised of scrap metal and electronics.

Henry's ship returns causing Carter to fear it maybe linked to the town's deadly electrical anomalies.

Allison's baby shower fetches her a load of eco-friendly gifts and the discovery of a drowned scientist in a location where drowning is impossible.

Global Dynamics sonic cleaning coincides with a phenomenon in which the citizens of Eureka develop a form of amnesia. Meanwhile, Allison goes into labor.

The first day on the job as temporary head of Global Dynamics proves daunting for Tess when a new Ice Age comes to Eureka; and a familiar face returns in the process.

Tess has a job offer from Australia, Zoe is prepared to leave for Harvard and Carter has a magnetic disturbance above Eureka to contend with, in the third season finale.