Zoe and Jo are back in Eureka. But things don't look the same on the episode "Omega Girls."
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Jo and Zoe return to Eureka in this scene. They are shocked by what they discover.
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Eureka Season 4 Episode 15 Quotes

Zane: Can I ask you something I can't really talk about with anyone else?
Henry: If it has to do with sexual mechanics while in zero-g... No.
Zane: Not that, although, now I have several questions.

Henry: That's disconcerting
Jack: It's bad isn't it? What is it? Subdermal hematoma, pheocromacytoma, concussion... Uh, there was a House marathon on last night.