Nolan, fresh off of his tour of dragging Tommy's body through the frozen tundra, storms on a tracking mission and finds Mordecai, the man drawn in Irisa's journal and the only thing that Kaziri is afraid of. Mordecai has his usual list of reasons why he can't go save the world, but Nolan's fists sure are persuasive. Their arrival in Defiance is greeted less with hurrahs and more with a collective "...meh." You see, Doc Yewll has cognitive crystals from the arkbrain and a scientific plan to take the big, digital meanie down. Nolan? Nolan has a dude with braids in his hair. They better hurry, though - psycho Irisa has already destroyed Manhattan and the rest of the world is next.
The downside of Yewll's plan is that Irisa must die so that everyone else can live. Amanda sees that they won't be able to enact Yewll's plan - which, by the way, will stop Kaziri from its worldwide, aggressive terraforming that destroys all animal life in its path - unless Nolan is locked up. She asks his forgiveness, in a sly mirroring of earlier events, and orders the E-Rats to throw him in the cell - and to take Mordecai, for good measure.
But c'mon - this is Nolan! And it's Irisa's life in danger! He's not going to let four pesky guards get in his way. He knocks 'em out in a melee - with some help from Kai - and they go to the spot where Irisa is playing with her floating rock garden, serenely orchestrating the destruction of life on Earth. Nolan fires a bullet that knocks away the gun pointed at Irisa, slaps cuffs on Amanda, knocks Pottinger out cold, then lays out Yewll, too. He and Mordecai catch Irisa and hold her down long enough for the silver artifact to leave her and enter Kai. The Kaziri is disarmed, but the terraspheres that float above the Americas, laying waste to Terran life, are in motion and must be stopped.
As the three musketeers enter the genocidal ship, Christie is back in Defiance getting to know the darker side of her mom - didn't take long! Pilar's anger showed up when she encountered pushback from the Tarrs on the subject of moving Christie into her house. Old rivalries die hard, it seems. Pilar tempted Christie and Alak away from their warm home with promises of a town where their mixed-species child would be treated equally, away from the E-Rep. The cause is helped when she reveals Datak's moved home, which pisses Christie off. But when the terrasphere storm starts turning the sky purple, and Alak wants to cancel the trip, Pilar pulls a gun, Quentin shoves Alak into the back of the truck, and they drive off into the night.
The Tarrs' new handmaiden, who saw them off, breaks her vow of confidentiality and tells Datak and Stahma about the kidnapping. They know there's one dude who can get into Pilar's head and figure out where they went: Rafe MacCaulay. He's not hard to find, being stuck at Camp Reverie, and the Tarrs arrive just as skittish guards are about to execute him and a host of other prisoners accused of rioting. Datak and Stahma cut fine figures in their white clothes, wielding automatic weapons and spiriting Rafe to their roller. They drive into the darkness, but will they find Pilar in time?
None of this will matter if Nolan, Irisa and Mordecai don't stop the terraforming. Kaziri is doing everything she can to stop them - throwing hallucinations at the artifact bearers, begging them to spare her life - but Irisa is furious that Kaziri made her kill Tommy. Nothing can stop her now. She and Kai lie down in the pilots' chamber, and step by instinctive step, cease all the machinations of Kaziri. The ship starts to crumble around them, and they urge Kai to run, but Nolan and Irisa are trapped inside the collapsing giant. They did it. They saved the world and sacrificed their lives. Berlin and Amanda mourn their fallen. Yet deep in the reaches of the ship, in a gelatinous pod, sits a human ark hunter and his Irathient daughter... maybe the tears shed for them will be replaced, one day, with something sweeter.