In December 1999, as Scotland prepared for the biggest Hogmanay of all time, a gruesome discovery was made by a police diving team on a training exercise in Loch Lomond. One by one, limbs from a cadaver were found and brought to the surface. Days later, a severed head was washed up on a beach in western Scotland and forensically matched with the limbs. Police soon had a prime suspect for the murderWilliam Beggs. But how had they been able to ascertain that it was Beggs right from the start? Just eight years earlier, Beggs had met Brian McQuillan at a disco and the pair had returned to Beggs'...