Bloodguilt

Nuclear fire brought endless night. The darkness hides invisible terrors known only as entities. Sheltered in the underground Ark 1 facility, Earth's last three hundred humans fear the dark above all else: the shadows hold an ancient, primal evil that can take control of a person, and against which humans have no defence.

Deep within Ark 1's miles of well-lit corridors, the lights begin to flicker and fail. Before a new darkness falls, a drug addict and a man with Down syndrome must reclaim the light and stop a final demonic Armageddon — and in the attempt they learn that someone inside Ark 1 had far more to do with unleashing the fiends than any of the survivors know.

Bloodguilt is the first part of Shadowless, a post-apocalyptic science-fiction horror story by the independent author Christopher D. Schmitz, published by TreeShaker Books in 2021. Stay in the light, stay alive.