A mysterious black sphere appears in the remote north of Scotland, draining the world of all light and energy. With humanity facing a slow, cold death, a desperate mission is launched: send a team inside to find its source and stop it.

John MacGregor, a grizzled veteran, joins the team. His blindness, once a personal tragedy, now makes him invaluable, as he alone can navigate the sphere's absolute darkness. With him is Eilidh Hunter, a military psychologist and the only one who understands the crippling mental toll the mission will take.

Inside the sphere, chaos reigns. Its power turns the team's fear and paranoia against them, leading to a bloody massacre. John and Eilidh are the only survivors, fighting their way out of the abyss and into a world they no longer recognize.

The sphere is gone, but so is humanity. In its place are cruel, deadly imitations of the people they once knew. Now, driven by the horrifying possibility that their failure may have been the very cause of the world's end, John and Eilidh must journey to find the last pocket of human hope.