You Will Know Me by Megan Abbott

Katie and Eric Knox have dedicated their lives to their fifteen-year-old daughter Devon, a gymnastics prodigy and Olympic hopeful. But when a violent death rocks their close-knit gymnastics community just weeks before an all-important competition, everything the Knoxes have worked so hard for feels suddenly at risk. As rumors swirl among the other parents, revealing hidden plots and allegiances, Katie tries frantically to hold her family together while also finding herself drawn, irresistibly, to the crime itself, and the dark corners it threatens to illuminate.