Summer, her husband Gabe, and Gabe’s nine-year-old son Charlie are headed to rural Pennsylvania for an annual get-together. This year, Gabe’s handsome younger brother Nick brings his new love interest—an actress named Hannah. When Summer meets Hannah, she recognizes her from an acting showcase they did together. The funny thing is, though, that Hannah claims to have no recollection of her. But soon after Nick and Hannah announce their lightning-fast engagement, a family member turns up dead of supposed natural causes. While she grieves, Summer starts to distrust the too-good-to-be-true Hannah, though she’s unable to convince any of the Keatons that their newest guest may pose a grave danger. As Summer investigates just what her future sister-in-law might have done to keep her perfect image intact, she begins to fear that her relative’s tragic death may be the first of many . . .