In the summer of 1993, gay men in London was being terrorised by a brutal killer. Colin Ireland, a loner from Southend had made a macabre resolution - to become a serial killer. For 3 months he hunted men, picking them up in a central London gay bar, taking them back to their flats and then strangling them. We talk to Ireland's ex wife and friends to uncover what made him tick. We also focus on the men tasked with catching him and how separate murder inquiries turned into a city wide manhunt.