The battle to save the inhabitants of Tethys from imminent destruction by the Authority's Decontamination Teams comes to a head, as Mac and Naela voyage off-planet to try and find a way to prevent what appears inevitable. At the same time Falcon is preparing for the worst, knowing that it may be up to him to make the ultimate sacrifice in case that Mac should fail.

But even if he succeeds, how can the people of Tethys continue their lives in the safety of their isolation, now that their existence is no longer a secret?