In a material stockroom, specialist Esther sees an outline of a figure when she kills the lights, however observes nothing with the lights on. She cautions proprietor Paul about the nebulous vision, whom he overlooks, and takes off. Paul is then pursued and grimly murdered by the figure. Paul's stepdaughter, Rebecca, lives far from her mom Sophie and sibling Martin. Sophie has a reported emotional sickness and misery that has reemerged, conversing with a fanciful companion.

One night, Martin sees Sophie conversing with a figure and is shocked, picking up a sleeping disorder. Rebecca takes Martin to her condo to secure him, against their mom's desires. That night, she stirs to discover the figure, scarcely evading its assault similarly as the building's neon sign turns on. The following morning, Rebecca discovers 'Diana' scribbled on the floor. She reviews Diana from her own particular adolescence, the reason she exited when her dad apparently deserted them.

Afterward, she softens up and sees documents about Sophie and Diana, and that she was slaughtered when presented to a splendid light for a trial. That night, Sophie has a motion picture night with Martin, however incorporates the figure, terrifying him. She reveals to him an anecdote about the figure, Diana, her companion when she was in a foundation, who had a strange condition that made her skin photosensitive. Martin sees Diana squatted above and turns on the light, getting away to Rebecca's before Diana can assault him.

Rebecca stands up to Sophie about Diana yet she denies the allegations. Rebecca, her beau Bret and Martin choose to remain overnight to ensure her. Rebecca goes to her room to accommodate; in any case, Sophie furtively passes her a note saying 'I require help' before Diana pulls her back in. Rebecca understands that she is being controlled and turns on every one of the lights in the house to keep her away.