Jaz's game developer colleagues celebrate the completed reboot of their horror-survival adventure Pulse, but security officer Eddie wants everyone to play the game for real.

As the building's inhabitants begin to suffer the fatal effects of the bomb, Errol, Caspar and newcomer Dom realize Jaz has a survival advantage that could save them all.

Caspar battles flashbacks; Errol slips further into his game persona; Eddie finds an ally; Jaz risks the crew's safety to rescue another survivor.

Game designer Felix delivers an apocalyptic warning; Eddie and Denny torment Caspar with memories; Dom and Jaz attend a bizarre tea party.

A new enemy shows off her influence; two survivors reveal their nightmarish connection to one another; Jaz's grip on reality frays.

Dark visions overwhelm Jaz; the chief antagonist finally reveals the story behind her despair and the chaos, leaving those who remain with uncertain futures.