Change is hard; and Carter is about to get more than he bargained for. Just as his life seems to be going smoothly, Zoe announces her acceptance into an early enrollment program for pre-med at Harvard. "Early" in this case means next semester. Neither Carter nor Lucas saw that coming. Carter tries his best to appear thrilled for Zoe while Lucas buries himself in his work with Henry. While Carter is reeling from the news, new girlfriend Tess reveals that she's contemplating a job offer that will start right after Allison returns - and it's in Australia. Worse, she neglected to mention it before they slept together. Ouch. To top it all off, Henry and Lucas' analysis of the data downloaded from Kim reveals the approach of "Nemesis", a neutron star that could reverse the earth's poles and bring about the end of the world. Carter is somewhat relieved to learn that this event is about 2,000 years off.
But the test of a new supercollider is happening today. Tess is excited, but Larry insists they are messing with the Laws of Physics. He predicts a fairly immediate end of the world. The collider breaks down in a dramatic explosion, and things do start to get genuinely weird. Julia finds Fargo stuck to the ceiling in his lab. Zoe takes part in an electronically controlled, Eureka-style diving competition, and when she plunges into the water, flames erupt. Even by Eureka standards, that's disturbing. Carter wonders if the collider might be the cause, but Zane says that it broke before it got started. Then Fargo - along with all the metal objects in Cafe Diem - gets stuck to a wall. Henry's investigations find a magnetic field fluctuating above the town. Someone, inspired by Nemesis, built a simulator to counteract its effect and it got out of control. Now, the very thing they were trying to prevent is about to happen, the spontaneous reversal of the Earth's poles, and global catastrophe will come with it.
Wormholes start popping up all over, threatening to rip Eureka apart unless Carter can stop them.