The fantastic Louis Theroux returns to our screens shortly with a brand new series for the BBC called 'By Reason of Insanity' where the presenter immerses himself in the world of Ohio’s State Psychiatric Hospitals. Never one for an easy challenge, is that Louis!

The series will see him meeting patients who have committed crimes, sometimes horrifically violent ones - while in the grip of severe mental illness. All of these people have been found Not Guilty by Reason of Insanity with their sentences to be served in maximum security psychiatric facilities where they receive treatment with the hope that one day they can be reintegrated into society again.

Over the course of this two-part series, Louis will be taking a closer look at mental illness in an attempt to understand how society cares for some of its most vulnerable and most dangerous members.

Undoubtedly intense viewing, but where Louis Theroux is concerned, it's always must-see.

'By Reason of Insanity' begins on Sunday 22nd March at 9pm on BBC Two.