Synopsis: The Resistance team is on the Mother Ship, with Elizabeth having given herself to the Leader as a bride as a kind of exchange for him to leave the planet and to take the Visitors back with him. Things don't work out as planned and many members of the team lose their life -- as well as that of the Star Child. The Leader is enraged and declares war on the planet, just as an ancient race from Earth arrive, having answered a signal Juliet Parrish and others had sent out into space when the war had first started.

Are they allies of the Visitors or are they here to help? And what will become of Earth and the Resistance as they gear up to fight the toughest battle yet...