In September 2007 someone flicked a lit match into a petrol can at a block of flats in Portsmouth. The fire that ripped through the building killed Kevin Holmes. Nine months later, his murder remains unsolved and there is nothing to indicate why he might have been a victim of arson. It's a tough case for Hampshire's Major Crime Unit, which has one of the lowest unsolved crime rates in the country. The case is handed to an experienced Detective Chief Inspector, the third senior investigating officer to take charge of the case. After nine months the trail looks cold. It's not long before the police make a series of arrests; but can they find the evidence to make the charges stick?