Wormholes start popping up all over, threatening to rip Eureka apart unless Carter can stop them.
The people of Eureka and being kidnapped and replaced by body-doubles one by one.
A malfunctioning experiment cuts Eureka off from the world and threatens to destroy all human life in town.
A mysterious file leads Jo to uncover a spy ring inside Eureka with devastating consequences.
Dosed with a smart drug Carter's genius gets out of control as he starts to re-write the laws of physics putting his friends and the whole town in danger.
Having thrown in his lot with Generation Bleu, Ao returns with Team Pied Piper to their headquarters in Switzerland. There, he finds himself out of his element and struggling to figure out how he fits in to their plans.