Hailey Malik life seems great, living with One Direction and having Zayn Malik as an adopted brother. Even coming from an abusive childhood, she stands strong and is living the dream. But what happens when she goes to America to study for a year and learns to sing. Can she keep it from her brother, best friends, and life long crush Harry Styles?

Rylee Devine is the little sister of One directions drummer Josh Devine. After an accident resulting in a loss of her parents, she is taken in by her brother and the band. As the spend the summer together, one of the boys finds himself falling for her, but will he break the 'Sister Rule' even if it means risking a friendship?