The people of Eureka are being kidnapped and replaced by body-doubles one by one unless Allison, Fargo and Zane can figure out how to avoid capture and save their town.

A familiar face returns to the 2nd Mass, but his intentions remain unknown. Meanwhile, a skitter is captured and brought back to the camp as a prisoner. And Hal bonds with Maggie as she begins to open up about her past.

Kagame pursues the first step of his new agenda – winning over the intellectuals and the grassroots dissenters. When Liber8 kidnaps the CEO of a major corporation, Kiera and Carlos must race an actual ticking clock to save the CEO from public punishment.

The Department of Justice arrives to investigate Grace, while Henry struggles with his conscience and Eureka is cut off from the world by a malfunctioning experiment that threatens to eradicate the town’s populace.

While on patrol together, Ben and Hal try to help a young boy and wind up having their bikes stolen. The hunt to recover them leads them to the discovery of something much bigger. Also, Matt is put in danger, and Weaver is reunited with a family member.

Harvey bristles at Daniel’s involvement on a lawsuit he’s handling, but their battle to one up each other threatens the case, leaving Mike caught in the middle.

Jack and Allison’s perfect honeymoon is interrupted when sabotage is discovered in Eureka. Elsewhere, Holly faces another hurdle to remain intact.

The 2nd Mass moves into an airport hanger. The Berserkers plan to get rid of Tom. While dealing with a loss of one of its own, the 2nd Mass receives a promise of hope from a mysterious visitor.

Kagame’s return begins with a reset of Liber8’s agenda, away from violence and towards blending into the community. But there may be a glitch – there is the possibility that if their ancestors living in this time are murdered, they might cease to exist. A test of this theory is devised with Kiera and her grandmother as the guinea pigs.

As Hardman makes it clear he’s back to stay, Jessica tasks Harvey with helping shore up support for her within the firm – but Harvey’s penchant for winning may create more enemies than friends.