Once again, the Mars settlement Rubicon faces off against dangerous and corrupt enemies. Dana, Jax, Darius, Lenny, Chuck and Zane return to the fray on a world that is their home but also their deadliest enemy. Isolated, vulnerable and hopelessly outgunned, it's a desperate struggle to hold off opposing forces. Saving the settlement comes down to the wire and their willingness to alter allegiances. Can they put aside their differences and save themselves? Or will their personal vendettas seal their fate?