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

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

Caspar battles invasive flashbacks, Errol slips further into his game persona, Eddie finds a useful ally in an embittered audio expert, and Jaz risks their safety to rescue another survivor.

Fellow game designer Felix delivers an apocalyptic warning, Eddie and Denny torment Caspar with his traumatic childhood memories, and Dom and Jaz attend a bizarre tea party.

A dangerous new enemy demonstrates her powerful influence, two survivors reveal their nightmarish connection to one another, and Jaz's grip on reality continues to fray.

With Jaz consumed by her dark visions, the "chief antagonist" finally reveals the story behind her despair and the recent chaos, leaving those who remain with an uncertain future.