Carl, Hekla, Eva, Donut, and Katia prepare a Vermillion-line subway train for a high-speed push to Station 101, where trapped crawlers are about to be overrun. Because the tunnel is too tight for a normal cowcatcher, Carl helps Katia reshape herself into a reinforced scoop-and-spike plow attached to the front of the engine, with rubber insulation meant to protect her from the electrified rail. The plan is for the train to kill or pin ghouls on Katia’s spikes while Donut and Hekla finish off anything still alive so Katia can absorb the bodies into her inventory.

Once Eva starts the train, the group immediately discovers the design is both effective and horrifying. Small groups of ghouls are liquefied on impact, but when they hit the larger stream near Station 72, gore and living body parts blast into the cab, and Katia is shocked unconscious by electrified remains wedged beneath her scoop. Carl uses healing scrolls to keep Katia alive, while the fairy healer Silfa hesitates until Carl forces her to act. During the chaos, Carl examines one of the new monsters and learns that the blister ghouls are being created by soul-crystal-powered ghoul generators, which confirms that the floor’s ghoul outbreak is part of a larger, self-sustaining system.

As the train pushes past Station 75 and onward, the group keeps mowing down scattered mobs, including armored creatures that break Katia’s spikes and exploding fairies that coat the plow in glowing residue. During the long ride, Carl receives messages from Elle and Imani, who used Station 60 to move around the transit system. They report that the festering ghouls at Station 48 merge into a giant province boss that fills the entire room, while wrath ghouls are massing at Station 36. Carl concludes the floor is developing multiple ghoul-based threats at different stations and that destroying the generators with explosives may be too dangerous because of the unstable soul crystals.

Near Station 101, Carl orders Silfa to heal Katia on a strict schedule because the incoming horde is much larger than anything they have already hit. When the train slams into the mass of ghouls, the plan nearly fails. The cab fills waist-deep with blood, limbs, and half-living monsters, the train slows under the sheer weight, and Carl, Donut, Hekla, and Eva are forced into close-quarters fighting just to stay alive. Silfa abandons her post and flees into the apartment section, leaving Carl to burn through his own healing resources as Katia’s health drops far faster than the visible damage should allow.

Donut finally realizes the cause when her special sunglasses reveal that Hekla has been mixing invisible phased bolts into her normal shots and embedding them in Katia. Carl orders Katia to disengage from the train, then pulls the hidden bolts from her body and identifies them as assassin ammunition that inflicts temporary amnesia and a severe bleed while disguising the true killer. The train reaches Station 101 with Katia barely saved, Eva injured, and hundreds of enemies still pressing nearby. As Carl tries to avoid an immediate fight, Donut ignores him and fires a full-strength Magic Missile into Hekla’s face after accusing her of trying to murder Katia.