Maddy starts interning for the colony's greatest scientist, and her life is put in danger when she discovers a terrible secret. Meanwhile, Josh makes a deal with the devil in order to solidify his plan to bring his girlfriend from the future to Terra Nova.

Taylor and Mira square-off in the jungle where he learns more about her plans and about his son. But then they both face a pre-historic enemy they must conquer together. Meanwhile, the "Sixer" mole scrambles to cover its tracks as Terra Nova goes on lockdown and Jim closes in. Also, Zoe faces a difficult decision as the Ankylosaur she has been caring for grows rapidly.