The D.O.D. has sent in a business shark to perform an evaluation of Global Dynamics' viability, and everything that could possibly go wrong, does. Including a drone, whose boosted AI turns it into a killing machine.
Carter is frustrated when he's told to investigate when robotic dogs begin exploding, believing it's a waste of his time. He's even more frustrated when no one else feels the earthquakes he's experiencing.
It's Allison's wedding day, and Carter is stuck in a time loop that causes him to relive it over and over. Unfortunately, there's no simple act that will right things, and the solution may prove very costly.
An opened sarcophagus unleashes a plague onto those who opened the tomb, and when it threatens Eureka, Carter has to devise a temperate fix. Meanwhile, Allison thinks she's gong crazy when she keeps seeing Nathan.
While Jack keeps having to rescue Lexi from a bumbling superhero, Zoe gets trapped while exploring an abandoned facility under the high school with her friends.
The appearance of a second sun makes election week in Eureka a little more intense, and gives Eva Thorne an opening that may mean the end of Global Dynamics.
All of Eva Thorne's secrets are revealed when she pushes for early destruction of the bunker. Zoe begins to experience the effect of the substance in which she slipped, leaving Carter to risk his life and job in order to save her.
Sheriff Carter interviews for a new job, Zoe braces herself for change, and someone works behind the scenes to make sure the new sheriff, a robot, fails.
Jo displays atypical behavior after a DNA scan malfunctions, unfortunately it's while she's interim sheriff when Carter is required to undergo a 48-hour DOD recertification test.
Carter finds out more than he bargained for when he's trapped in an alternate dimension with the new scientist. Meanwhile, the father of Lexi's babies comes to town.
A bowling tournament brings a rival team from Area 51 to town, but when a practical joke goes too far Jack may be the town's only hope for survival. Meanwhile, Lexi is not happy when Duncan returns.
Jack, Henry, and the rest of the GD team try to figure out why teenagers are building towers out of junk, the signal moves closer faster, and Fargo's old car doesn't like being dumped.
Henry tries to figure out why his spaceship came home, why it recreated Kim and especially how he's going to relate to her. Meanwhile the sheriff's office tries to return all the property the spaceship used to create its boson safety net without too many mix-ups and then how to get it all back to save the earth.
Women who attended Allison's baby shower are turning up drowned and with no apparent source of water. There doesn't seem to be a way to extract the data stored in Kim's body without destroying her. Jack develops a severe case of sympathetic pregnancy.
Jack and Allison are trapped within the Global Dynamics building during a countdown for a sonic cleaning. Fargo messes with the memory recording system Dr. Fontana has been working on, which accidentally leads to widespread amnesia.
Carter deals with a new magnetic force tearing apart the town, Zoe gets unexpected news about her college application and Tess drops a bombshell about a job offer.
