In northern Norway, ex-photographer Freya Halvorsen investigates a mysterious ancient lens that removes shadows when placed before a light source. She meets Ingrid, a young girl who cast no shadow after an encounter with the lens, and Rasmus, an engineer working to replicate the technology. As Ingrid gradually fades from perception entirely, Freya discovers the lens was created by the Order of the Constant Light—a secret society that has spent millennia "purifying reality" by erasing people and events they deem anomalies from human perception. Freya learns her missing brother Lars wasn't lost in an accident but deliberately erased after discovering the Order's activities. After being partially erased herself, Freya joins with others affected by the lens to fight back. They create a counter-device that reverses the erasure process, restoring shadows and bringing back those who were completely erased, including Ingrid.