As their parents head out for a date in the city, the three young Thompson children immediately take to their new babysitter, Anna, who seems like a dream come true: shes sweet, fun, and lets them do things that break all of their parents rules. But as Annas interactions with them take on a more sinister tone, the kids realize that their caretaker may not be who she claims to be. Soon its up to big brother Jacob to protect his siblings from the increasingly nefarious intentions of a very disturbed woman whose weapon is trust, and whose target is innocence.