Filmmaker Robb Leech is desperate to know how his stepbrother Rich could make the transition from middle-class white boy, to convicted terrorist. The two grew up in the English seaside town of Weymouth, Dorset. When Rich became a radical Islamist in 2009, Robb decided to enter his stepbrother's world of beards and burkhas, where people talked about fighting jihad and implementing sharia. The result was Robb's acclaimed documentary My Brother the Islamist. Then in 2013, Rich was convicted of preparing acts of terrorism, and sentenced at the Old Bailey, to six years in prison. The court had been told that Rich now know as Salahuddin, had been preparing to join a Taliban training camp in Pakistan, in readiness to fight jihad on the battlefield, in Afghanistan. Robb decided he must find out what triggered his stepbrother to cross the line, and become a convicted Islamist terrorist.