With unprecedented access, documentary filmmaker Robb Leech enters Europe's biggest Muslim community, in the heart of London's East End. Leech first came to the East London Mosque with his stepbrother. He'd converted to an extreme brand of Islam, and in 2013 was convicted of preparing terrorist acts and jailed for six years. Now the Mosque has invited Robb back, to find out what life is really like inside for some of the two million people who attend every year.