A man bursts into flames. Elsewhere, Carter and Deacon are reaccustoming to the timeline restored in "Once in a Lifetime."

Carter requests Stark's help after Fargo accidentally activates a personal force field, which causes mayhem.

An isolated deep freeze trigger causes a chain reaction of sudden weather changes in Eureka.

After receiving a hit to the head, Carter finds that he is in a parallel Eureka. He discovers that the residents of the parallel Eureka are disappearing.

Space debris threatens Eureka's existence after it accumulates into a large cloud. Carter investigates in an effort to avert potential disaster.

A toxic spill seems to cause Eureka's residents to share their dreams. Initially the situation is amusing, but turns dire after the dream sharing is discovered to have a lethal attribute. The situation becomes more complicated, when Carter finds out that the spill is not the cause.

A man who turns out to be Fargo's grandfather has been cryogenically frozen for 50 years. He is awakened from his slumber by accident with no recollection of how he was frozen. In addition to that, it seems that he is the father of lots of technologies at Eureka.

An experiment about the big bang theory seems to be the cause for Eureka's finest to become dumber and dumber, including everyone involved in the experiment. When it comes to the verge of destroying Global Dynamics, the fate of the town lies in the hands of Jack Carter and the team of scientists he assembles, amongst them the newest member of the town, an anti-social genius.

Strange happenings and spreading radiation at Global Dynamics lead to speculations that an abandoned research project concerning invisibility might have been revived. When Sheriff Carter accidentally becomes involved, the effects of invisibility threaten his life.

Zoe and her friends lose their voices, but whatever is causing the symptoms has an even worse effect on Allison and her only hope comes from an unusual source.

Eureka's air-conditioning system develops a fault, causing sexually tense situations, when the female residents suddenly become attracted to Carter due to bacteria.

The town along with its residents mysteriously start to deconstruct. The prime suspect is an artist who couldn't get along with Stark when he was working at Global Dynamics.

Carter and Stark must work together as an aggressive virus is sweeping across Eureka, while Kevin's life is in danger.