When a massive sinkhole mysteriously opens in Los Angeles, it tears a family in half, separating mother and son from father and daughter. When part of the family finds themselves in an unexplainable primeval world, alongside a disparate group of strangers, they must work to survive and uncover the mystery of where they are and if there is a way back home.

Ben Hall is drawn back into bushranging by the reappearance of his old friend John Gilbert. Reforming the gang, they soon become the most wanted men in Australian history.