West Side Story is a musical loosely based on Shakespeare's Romeo and Juliet. Set in Manhattan's Upper West Side, the musical explores the rivalry between two teenage gangs of different ethnic and cultural backgrounds. The young protagonist, Anton ("Tony"), who belongs to the white gang, falls in love with Maria, the sister of the leader of the rival Puerto Rican gang. The dark theme, sophisticated music, extended dance scenes and focus on social problems marked a turning point in American musical theater. Bernstein's score for the musical has become extremely popular, including "Something's Coming", "Maria", "America," "Somewhere," "Tonight", "Jet Song", "I Feel Pretty", "One Hand, One Heart", and "Cool"