Three years ago, SKYE's sister ASHTON went ghosting at an eerie house, the resident fired shots, and Ashton came home with a bullet in her head. Though her sister has no memory of the incident, Skye has long been suspicious Ashton pushed things too far that night. Now seventeen, Skye must choose between an acceptance letter from N.Y.U. and an unspoken obligation, that may be partially her own, to enroll at State with her brain-injured sister. Determined to make her sister see it mattered what she did that night, Skye challenges Ashton to help her investigate what really happened.
Their probe uproots memories of the sisters' relationship before bullets. Skye still resents Ashton, the charismatic cheerleader who deserted her after their parents' divorce, and desperately wants her affection. Dogged by years of silence, Skye begins adding to the memory book Ashton uses to cope with her brain injury, hoping if Ashton has to take responsibility for the kind of person she was, maybe Skye won’t have to. When Ashton begins writing back, the sisters' memories fly back and forth—weapons, dares, and olive branches—with the power to heal the sisters or end them forever.