On Denali, Ptolemy finishes repairing the first of the abandoned cymek walkers. Grieving Dr. Elchan and working alone, Ptolemy channels his obsession into restoring a broken machine that he believes can defend civilization against Butlerian destruction.

Because the original thoughtrode neural interfaces remain too complex for Ptolemy to use, he builds a sealed control cab beneath the crablike machine body. After testing its life-support and hard-linked controls, Ptolemy powers up the walker and awkwardly learns to move its six legs by conventional mechanisms.

Ptolemy exits the Denali hangar into the toxic, chlorine-filled landscape and ventures beyond the research modules. The secret base had never been thoroughly explored, since Josef Venport’s researchers cared more about hidden work than mapping the hostile world, but Ptolemy searches specifically for old cymek technology he can salvage.

Past the landing field, Ptolemy discovers a vast graveyard of deactivated cymek bodies and then more collapsing structures with many additional armored walkers. The find transforms his hopes: Ptolemy imagines restoring the machines into an army capable of resisting Manford Torondo, Swordmasters, and Butlerian mobs.

As Ptolemy imagines using the walkers to crush Anari Idaho and make Manford witness Butlerian slaughter as revenge for Elchan’s death, he recognizes the current cab controls are too clumsy for real combat. Ptolemy concludes that he must master or recover direct neural interfaces so rational humans can operate the machines effectively and prevent a new Dark Age.