Karst’s open mic broadcasts his drawn-out struggle outside until a spider lands on his faceplate and the feed goes silent. Inside, Lain frantically coordinates scattered defenders while sensors fail and breaches multiply. A sudden stillness reveals the vents have stopped: Vitas has shut down life support to contain a spreading spider-borne agent.

From her sealed test chamber, Vitas reports assistants collapsing and a widespread contaminant. She promises to route clean air and push ahead with a counter-bioweapon. Holsten relays Lain’s shifting safe routes to fighters like Alpash, who reports brief successes before contact degrades.

As spiders cut through bulkheads and ducts, safe zones fall as fast as Lain builds them. Vitas’s calm breaks into terror: spiders reach her lab, eat through the glass, and her screams end abruptly. Elsewhere, lights die and comms fail; Holsten can no longer raise Alpash. The ship’s defense unravels.

Lain and Holsten prepare for a last stand, donning masks while the hatch warms under a cutting attack. Karst’s voice returns, eerily tranquil, claiming the spiders are like humanity and that “we’re coming back in now.” Chemical haze creeps in as a hole opens at the hatch’s base.

Spiders peer through clear masks. Holsten lifts Lain’s metal stick but chooses instead to hold her. With Karst urging his people to “pick up the pace,” the spiders surge through the breach and leap, ending the final defense.