Diana is a suburban wife and mother who begins to question her seemingly perfect life, and perhaps her sanity, on the 15th anniversary of a tragic high school shooting that killed her bestfriend. Diana was a vibrant high schooler who, with her shy best friend Maureen, cut class, fantasized about boys and vow to leave their sleepy suburb at the first opportunity. Now, however, Diana is haunted by the increasingly strained relationships she had with Maureen as the day of the school shooting approached. These memories disrupt the idyllic life she now has with her professor husband Paul and their daughter Emma. As older Diana's life begins to unravel and younger Diana gets closer and closer to the fatal day, a deeper mystery slowly unravels.