After repairing the safehouse's door controls and stopping the invading zombies, Chuck Greene runs across Tyrone King, who has somehow gotten free of his restraints and is under attack from a lone zombie straggler. Chuck kills the zombie, but not before Tyrone is bitten. Knowing he will turn soon, he begs for a shot of Zombrex. After securing Tyrone once more, Chuck reviews some of the footage that Rebecca Chang shot while down in the underground tunnels, where he notices that the gas is coming from the underground. Suspecting that this might be the source of the mutagen gas covering the city, Chuck heads out to investigate.