Such a Quiet Place by Megan Miranda
Welcome to Hollow's Edge - a picture-perfect neighbourhood where everyone has each other's backs. At least, that's how it used to be, until the night Brandon and Fiona Truett were found dead... Two years ago, branded a grifter, thief and sociopath by her friends and neighbours, Ruby Fletcher was convicted of murdering the Truetts. Now, freed by mistrial, Ruby has returned to Hollow's Edge. As her return sends shockwaves through the community, terrified residents turn on each other, and it soon becomes clear that not everyone was honest about the night the Truetts died.