On scholarship at a prestigious East Coast college, Mabel Dagmar is befriended by her roommate, the blue-blooded Genevra Winslow. Invited to spend the summer at Bittersweet, a cottage on a Vermont estate, Mabel falls in love with the moneyed laughter that carries across the still lake while fireworks burst overhead. Soon she has everything she's ever wanted: friendship, a boyfriend, access to wealth, and the sense that she belongs. When a discovery leads to violence and reveals how the Winslows keep their power intact, Mabel must either expose them and face expulsion from paradise, or keep the family's dark secrets and make this world her own.