On a cold December morning, the limbs of a young man are found by chance in Loch Lomond by police divers on a routine training exercise. News of the grim discovery at one of Scotland's most famous beauty spots quickly reaches the tabloid press, and speculation of a gangland killing ensues. Then, eight days later, the severed head of the young man washes up on Barassie Beach, 60 miles away on Scotland's south-west coast.The victim is identified as 18-year-old Barry Wallace, from Kilmarnock, who had been reported missing after a night out with work colleagues. Strathclyde Police launch a murder probe, with Detective Superintendent John Geates appointed senior investigating officer. Geates and his team quickly identify a prime suspect, William Beggs, and armed with a warrant, raid his flat. There is no sign of Beggs, but the police make a shocking discovery.