Get ready to rock! In this upbeat musical, Barbie stars as Courtney, a princess whose world is turned upside down when she switches places with Erika, a famous rockstar.Get ready to rock! In this upbeat musical, Barbie stars as Courtney, a princess whose world is turned upside down when she switches places with Erika, a famous rockstar.Get ready to rock! In this upbeat musical, Barbie stars as Courtney, a princess whose world is turned upside down when she switches places with Erika, a famous rockstar.