In the aftermath of World War II, Grace Stewart lives with her two photosensitive children, Anne and Nicholas, in a remote country house on the Channel Island of Jersey. The children's ailment prevents them from being exposed to natural light, compelling Grace to establish strict rules: no open doors, no forgotten curtains, and only lamplight during the day. Their quiet lives are disrupted when Grace hires a trio of new servants – Mrs. Bertha Mills, Mr. Edmund Tuttle, and a mute girl named Lydia, to help run the house after the unexplained disappearance of the previous staff.

Tensions escalate when mysterious occurrences begin to unravel the fabric of their secluded existence. Anne claims to see strange apparitions and persistently shares stories of her encounters with 'the others,' which Grace initially dismisses as a child's imagination. Yet, as unaccountable noises, inexplicable shifts in the house's state, and the children's increasing agitation persist, Grace begins to confront the possibility that their home may be inhabited by unseen entities. With events becoming progressively more unsettling and the fog-shrouded house growing ever claustrophobic, Grace's skepticism turns to desperation, compelling her to investigate the haunting mysteries that engulf her isolated abode.