A mysterious young woman, Katie (Nicky Whelan), and her daughter move to a new town to escape her past and quickly befriends Angela Morgan (Gina Gershon), a mother of one who longs for a more prominent family. As their lives become intricately entwined, Angela and her husband, Brian, (Nicolas Cage), invite Katie to live in their guest-house to serve as their nanny. Over time, the blossoming friendship between the two women spirals into a dangerous obsession as Katie becomes overly attached to the Morgans' daughter. Enduring lies and manipulations, Angela and Brian realize that sweet Katie is trying to destroy their family from within.