We never cease to be amazed by Louis Theroux, who's put himself in some of the most dangerous, unusual and uncomfortable situations in the name of fantastic journalism.
But his latest series, By Reason Of Insanity, is a new frontier even for this veteran. In it, he'll go behind bars at the Ohio State Psychiatric Hospital, to speak to people who have committed violent crimes and been declared not guilty due to the mental illness – and to examine how society treats these vulnerable yet dangerous members.
By Reason of Insanity: Part 1 will be broadcast on 22 March on BBC Two at 21:00 GMT. You can catch up via the BBC iPlayer