"A tense, simmering, fast-paced mystery."—Megan Miranda, New York Times bestselling author of The Last House Guest and The Girl from Widow Hills The New York Times bestselling author returns with an unsettling but riveting psychological thriller about a captivating woman who joins a family and threatens to upend their picture-perfect lives. They had everything they needed for a perfect family vacation: close-knit relatives, a bucolic setting . . . and a murderer in their midst? Summer's looking forward to a break from hustling for acting work in Manhattan when she, her husband Gabe, and Gabe's nine-year-old son arrive at the annual family get-together at her in-laws' sprawling estate. On the agenda are leisurely gourmet meals, tennis matches, and plenty of relaxation by the pool. But this year, Gabe's brother Nick has invited his new flame Hannah, whom Summer immediately recognizes from a few years before. Oddly, her brother-in-law's girlfriend claims not to know her. Yet she charms the other family members, and after Nick announces that he's proposed to Hannah, Summer doesn't have much choice but to grin and bear it. Then the reunion is rocked by tragedy when a family member is found dead. Though the doctors attribute the loss to natural causes, a grieving Summer fears that the too-good-to-be-true Hannah is involved, even as Gabe dismisses her suspicions. How far will Summer go to expose the truth? As she investigates just what Nick's fiancée might have done to keep her perfect image intact, she begins to fear that the first death might only be the beginning . . .