When the Russo family returns home from vacation to discover their nanny, Ruby, has unexpectedly passed away, Matthew takes the news the hardest. After weeks of reeling, his three best friends decide to cheer him up with a night of junk food, prank calls, and scary movies. But their plans for a sleepover are jeopardized when Matt's single mother-unable to take any more time off of work-is forced to hire a new nanny on the fly to watch over Matt and his younger sister, Judy.

The sitter, Miss Swan, however, is all too happy to have the boys over. And although she seems like the perfect babysitter, letting the kids eat whatever they want and mostly leaving them alone, there's something about her that Matt doesn't trust. He thinks she may actually be the witch from local legend-the one who torments children into the night and then eats them. Is he just having a hard time dealing with Ruby's replacement, as his friends suspect? Has he watched one too many scary movies, as his mom fears? Or are he and his horror-buff friends in for the fright of their lives as they come face-to-face with a real monster?