The infected UN flagship becomes a zombie-packed plague-ship; Holden boards it for Nguyen's codes and detonates its self-destruct, ending it in white fire.
The UNN Agatha King, holed and infected in the Io battle, has become a plague-ship: its bioweapon pod struck aft, a monster made for the reactor room (killing the Marines who tried to stop it), and the protomolecule herded the thousand-plus crew into the forward galley and remade them into intelligent blue-eyed zombies. Radiation floods the hull from the vented reactor; blue fireflies drift in the corridors. Holden boards her via the Razorback using Souther's master override, fights through the zombie swarm to the CIC, executes the surviving Nguyen for the launch codes, and finds her anti-boarding self-destruct — a no-timer fail-safe.
The infected sailor Larson presses it after Holden escapes. The Agatha King vanishes in a ball of white fire, taking the protomolecule horde with her, as Holden nears the Rocinante.
A massive UN Truman-class dreadnought, undamaged-looking forward but radiation-flooded and zombie-infested within, ending in a brief star of white fire.
Nguyen's infected flagship, destroyed by its own self-destruct to contain the protomolecule after Holden takes the codes.