Tree-surgeon turned film-maker Robb Leech is an ordinary white middle-class boy from the Dorset seaside town of Weymouth. So too is his step-brother Rich. But a little over a year ago, Rich became a radical Islamist, who now goes by the name of Salahuddin. He associates with jihadist fundamentalists and believes the UK should be ruled by Sharia law.
Filmed over 12 months, Robb sets out to reconnect with his extremist step-brother; to find clues to what led Rich to become Salahuddin. Robb talks about his relationship with Rich as they were growing up, including home footage. Through the brothers' story, the viewer is taken into a previously unseen world of radical Islamists, living in Britain.
'My Brother the Islamist' broadcasts Monday 4 April, 9pm on BBCthree.
To read Robb's blog about the programme, follow this link bbc.co.uk/news/uk-12900460