AceShowbiz -

Expect an epic battle between two groups of humans in the two-hour season finale of "Terra Nova". It all stars after the mysterious Phoenix Group from 2149 travels back to the past and makes its move to pillage the land with the help of Lucas and Mira. Determining to save the place they call home, Jim and Taylor team up in a last stand against the evil guys.

The ultimate episode will open with an explosion as executive producer Rene Echevarria recently revealed, "Our evil guys, the Phoenix Group, will send somebody through the portal with a bomb, and it explodes." Jim is hit by the blast and wakes up three days later only to find out that Phoenix soldiers have taken command of the colony.

The said outing will also feature the demise of two characters, one of which is "a person who is without family will willingly go to [his or her] death in order to help the Shannons survive," executive producer Brannon Braga teased. While Allison Miller who plays Skye could not spill the detail, she gushed that the scene is "heartbreaking" and "so, so sad."

"Terra Nova" season ender will air Monday, December 19 starting at 8/7c on FOX. It will also include an unexpected return to 2149.