One day when visiting the pier with his daughter Mara, Grayson March encounters a young woman, Jenna Mayer, who saves Mara after she falls into the water. Touched by Jenna's concern for Mara, Grayson invites Jenna to stay in his guest house at the rear of his lakefront property, to the discomfort of his mother-in-law Evelyn. Mara warms to Jenna as she seeks a mother figure as Grayson's wife died at childbirth, leaving Grayson a widower. Jenna's life is shrouded in mystery, and this causes Grayson angst, as she refuses to discuss this in any way. Is Jenna a real threat to the March family's happiness that will bring them nothing but heartache?