Astrid Johansen swore she would never return to Heron Bay, Washington. In that idyllic coastal town, her little sister, Nina, drowned in a reflecting pool under Astrid's watch seventeen years ago. Though guilt has kept her away, Astrid can't ignore her aunt Maude's urgent plea to come back. Maude claims to have found a letter that will change everything about the past. When Astrid arrives in Heron Bay, she finds Maude unconscious, perhaps the victim of an attack. As Maude lingers in a coma, Astrid uncovers alarming evidence that Nina's drowning that tragic night was no accident. But in a town rife with secrets, and in a family still fractured by grief, who knows the truth? Astrid's investigation leads her down a trail of dark memories, lies, and betrayals that will shatter her perception of everyone she thought she knew-even herself.