Orson Grier suffers from severe acquired prosopagnosia?face blindness. To his brain, human facial features are a meaningless, shifting blur. He identifies people solely by their clothing, gait, perfume, and voice. Orson works as the night auditor at Astraea Chasm, an ultra-luxury stargazing resort built deep inside a remote desert slot canyon. Certified as a "Dark Sky Preserve," the resort strictly prohibits external lights, making it a haven of pitch-black tranquility.

But when a massive flash flood washes out the only access road, Orson and eight wealthy guests are completely trapped. The terror begins when Orson accidentally walks into the geothermal pool area and interrupts someone frantically washing a massive amount of blood off their hands. The killer is completely naked and remains dead silent. Unable to read faces, and with no clothes or voice to identify them, Orson flees in terror, realizing the murderer could be absolutely any of the guests.

The killer quickly realizes Orson's neurological weakness and begins a terrifying game of psychological torture, swapping clothes with dead victims and mimicking their voices to scramble his perception. Discovering the killer is actually a corporate "fixer" hired to assassinate the guests, Orson knows he cannot trust his broken mind. Cornered in the resort's towering observatory, Orson must use the desert environment against his tormentor. He must weaponize the resort's heavy-duty industrial UV blacklights to expose the glowing, blood-soaked monster in a desperate final trap, or become the next victim in the dark.