In 1996 a gunman opened fire from the top of a multistory carpark killing passersby on Whitewater High Street. Since known as the Whitewater massacre, one of the victims was a tactical squad police officer, Sgt. Nick Patterson, Supt. Peter Boyd's best friend. Patterson's police-issued Glock pistol disappeared and was the weapon used to kill him. The Glock disappeared that day but is found seven years later by two boys some 10 miles from Whitewater. Boyd and his team are assigned to solve the mystery of the vanishing gun as the convicted sniper's solicitor is calling his client's conviction into question. As the investigation continues, the team begin to discover anomalies that may in fact mean the convicted killer, Carl Mackenzie - who always maintained his innocence - may have been wrongly convicted.