Grace and Harris must forge an alliance when their children's lives are in jeopardy. Also, Liam presents Jillian with an unusual proposal.

An illegitimate government now complicates efforts to save mankind from Sampson, the killer asteroid. After the discovery that President Mackenzie is still alive—but had been poisoned—Harris, Grace, and Darius are scrambling to topple the new administration of President Bennett. Meanwhile, Darius is running out of time to finalize his plans for the ark. Will there be a real future for Liam and Jillian? Will Darius, who was disqualified from his own escape plan, find another solution?