While under the influence of a smart drug, Carter becomes a genius like everyone else in town and starts to change the laws of physics. Unfortunately, his condition soon endangers all of Eureka, including Allison’s brother who is in town just to meet his new brother-in-law.
Tom is haunted by memories of his time with the aliens. Pope plants seeds of doubt about him among the group. Ben’s hatred for skitters grows. The 2nd Mass locate a bridge that will help them cross the river to safety ahead of an impending attack.
Weaver is still in command of the 2nd Mass, while Anne continues to serve as medic. They have seen many battles and are a much leaner unit now. Pope has taken command of the Berserkers, a renegade group within the 2nd Mass that Weaver doesn’t fully trust.
A scientist who is working on developing a source of clean energy is found murdered. The list of suspects leads Kiera on a journey that takes her to a precarious place – deciding between the right thing to do and the preservation of the future.
Sarah and Holder’s investigation comes to a close. Meanwhile, Richmond sets out on a bold new course; and a surprise source helps bring closure to the Larsens.
Oblivious of the fact that Trevor approached Jessica, Mike’s on top of the world after Harvey entrusts him with closing a major lawsuit for the firm.
Carter’s romantic surprise for Allison turns deadly when they’re trapped in a sinking marine lab with time and oxygen quickly running out.
Kiera and Carlos investigate a series of mysterious murders in which victims have been drained of endocrine fluid only to discover that the crimes were committed by Liber8 in an effort to save Travis, their leader. Kellog tries to make a truce with Kiera by delivering her a gift, one that could cost her and Carlos their lives and will lead to Kellog’s expulsion from Liber8.
Sarah and Holder close in on the murderer. Meanwhile, the Richmond campaign preps for the election; and the Larsens seek to get their lives back in order.
Fargo is convinced that Holly is still inside of the Matrix computer, but the DOD is determined to wipe its hard drive clean — losing Dr. Marten forever.