Dead on Delivery — George Douglas

On his paper round one morning, Ted Blake finds two of his favourite customers battered to death. Suspicion immediately falls on him, but when Detective Superintendent Trott and his Homicide Squad take over they find that characters from the criminal underworld appear to be involved. Detective Inspector 'Bonny' Lee, the Investigating Officer, is literally taken for a ride before reaching the outcome of one of the most complicated double-murder cases the Squad has ever tackled.