A night security guard in a corporate skyscraper discovers an elevator button labeled “0” appearing only after midnight. When pressed, the elevator descends far below the building into a hidden underground level that officially does not exist. Floor Zero contains abandoned offices frozen in time, flickering computer screens, and records of employees who vanished years earlier. Strange humanoid figures wander the hallways repeating fragments of conversations. The guard uncovers a secret experiment involving consciousness transfer and alternate realities conducted by the company decades ago. Every midnight, the experiment briefly reactivates.