Last year Dan Murdoch won the BBC Fresh competition for first time directors with Transsexual Teen Beauty Queen which has been nominated for a Grierson Best Newcomer of the World Award. He has spent the last six months trailing a trio of teenage American evangelists who believe much of the world's population is possessed by biblical demons, and they have the power to banish them to hell. Watch Teen Exorcists on BBC3, Sept 12, 9pm.

‘Teen Exorcists’ offers a compelling insight into the controversial and dramatic ritual of exorcism – from the perspective of three teenage girls.

Brynne, Tess and Savannah initially appear as archetypal all-Americans. However, a shared passion for exorcism sees the girls devoting their free time to what they refer to as ‘kicking some demon butt’.

Mentored by Brynne’s father, celebrity exorcist Rev. Bob Larson, the girls have spent their teenage years training to become a crack team of demon banishers armed with bibles and silver crosses. On a mission to bring the practice into mainstream culture, we are invited to follow the girls as they take their spiritual warfare on the road, conducting private and public exorcisms in return for donations.

Director Dan Murdoch gains unprecedented access into the girls’ universe as they travel to the Ukraine and, most significantly, to London – which they believe to be the universal hot spot for satanic activity.

Filmed over the course of six months, Murdoch’s documentary unpicks the intensely theatrical nature of exorcism alongside delving into the personal lives of the three girls; an exploration which leads to a fascinating final question - are these girls truly miracle-workers or simply shameless frauds?