Brynne, Tess, and Savannah are seemingly typical American girls who love horses, karate, and detective stories. However, they harbor a secret: they are exorcists. The girls believe widespread possession by evil spirits fuels societal problems like addiction and despair. Touring the U.S., they perform public exorcisms on those they believe are afflicted. Now, they travel to London, a city they consider deeply spiritually corrupt, to continue their fight against demonic forces. The question is: how will Londoners react to these fervent American exorcists?