A brother turns on his brothers in this low-budget thriller set at a time when drought has laid civilization low. Callan Mulvey (“Power”) stars. It’s not easy trying to be the next great Nashville country-music star when you’re stuck living in Scotland. That’s the premise of Tom Harper’s film starring Jessie Buckley as a singer with big dreams and big talent. The film has been lavished with critical acclaim for Buckley’s persuasive performance.