Willow is in need of an escape. A former sitcom star, she's been publicly shamed on the internet after posting something she really shouldn't have. She checks in to Camp Castaway, an adults-only retreat based at an old campground in the woods. It's the first night and the campers gather round the fire and decide to tell some ghost stories. That's when Willow hears the tale of Knock Knock Nancy. A local urban legend about a witch, brutally beheaded in this very woodland. They say her restless spirit knocks on doors late at night. If you answer, she'll take your head. Willow doesn't believe in ghosts, after all, they're just stories. But the next day, a camper has vanished under mysterious circumstances. And then that evening, in her cabin, Willow hears it. Knock, knock, knock.