Rent To the Power of Three (Tess Monaghan Mysteries)

Murder destroys a tight high-school clique in this standalone by the author of the Tess Monaghan mysteries. In affluent Baltimore suburb Glendale, three girls rule the high school: gorgeous super-student Kat, star actress Perri, and cheerleader Josie. After a mysterious shooting in the girls' bathroom, Kat is dead from a bullet to the heart, and Perri is in a coma with her face partially shot off. The gunshot wound in Josie's foot doesn't prevent her from speaking, but what she does have to say is remarkably unhelpful to the investigators on the case, Baltimore County detectives Harold Lenhardt and Kevin Infante. So what happened, and why?