Following an experiment on the artifact, Eureka warps to 2010. However, temporal anomalies begin to cause problems for Eureka, which leads to a shocking revelation.

S.A.R.A.H.—the artificial intelligence that runs Carter's house—takes him and a group of residents hostage in an intervention to keep Carter in Eureka. Meanwhile, S.A.R.A.H.'s root program B.R.A.D. activates and turns the situation deadly.

Sheriff Carter and Zoe are the only ones unaffected when Eureka's residents begin to behave strangely, so father and daughter team up to search for the cause.

A nanotech experiment escapes from Global Dynamics. The project, which bridges the gap between computers and human brains, threatens to overrun Eureka when it begins duplicating Stark.

When the return of Eureka's star pupil causes problems all over town, Stark is forced to make a hard choice. Meanwhile, Carter attempts to track down Zoe who has run off with the former resident.

Carter investigates an unusual car accident. Meanwhile, Stark is under stress to produce results on a project.

After Fargo and Spencer accidentally activate a doomsday device, Carter must help Dr. Irwin Thatcher, an aging scientist, to shut down the machine.

After a lab accident, Global Dynamics researcher Carl Carlson is expelled from Eureka due to lack of results. Later, it is discovered that the accident has unlocked hidden abilities in Carl. Meanwhile, Jack does his best to avoid a physical.

Spencer is apparently abducted by aliens and then returned to Earth the next day inside a crop circle. Also, the town is visited by Congressman Arnold Faraday, whose committee is responsible for Eureka's government funding.

Jack Carter accidentally shoots Henry while suffering from short-term memory loss, and the visiting scientist whose wife is Henry's old flame may hold the only clues into that incident and the increasing memory losses occurring both in town and at Global Dynamics just as an important military contract comes due.

Carter and the other citizens of Eureka attend the funeral of Susan and Walter Perkins. Much to their surprise, Susan makes a return to Eureka as a woman who is very much alive!

A car accident leads U.S. Marshal Jack Carter into the unique Pacific Northwest town of Eureka.

After a strange accident sidelines Eureka's sheriff, Jack Carter takes over the investigation into the mysterious phenomenon that led to the death of a resident.

Carter learns about the secret purpose of the town while trying to re-establish a connection with his angry and bitter daughter, Zoe. He develops a friendly working relationship with government liaison Allison Blake and meets some of the more eccentric residents of Eureka.