Despite the fumes from lorries and the whine of speeding cars, much of the M5 is a pleasant enough road to drive. Once the heavy traffic of Birmingham is left behind, the road cuts through the gentle hills of the Malverns and central Gloucestershire. Two splendid bridges are soon spied crossing a major river and taking traffic into the Principality of Wales, thus saving drivers a long detour to the north.This major motorway runs from England's second city, Birmingham, in the Midlands, the central industrial heartland of the country, down to the holiday destinations of the South West, including Somerset and the chocolate box villages of Devon. The M5, six lanes of speeding traffic, passes through just one other major city on its route - Bristol, which sits high up on the Severn Estuary, the wide river mouth which separates England from south Wales. Clifton, Bristol's most exclusive suburb, is cut into the hills and another long bridge soars over the tidal estuary below. Then the hills become bigger, and holiday resorts begin to be highlighted on brown motorway signage. To the west sit the highlands of Exmoor, home of the mythical beast and real cream teas, and, later, the even more dramatic Dartmoor, whose barren moors are glorified in the works of writers such as Daphne Du Maurier and Sir Arthur Conan Doyle. But the road is not all beauty. Its Thornberry section is one such less than attractive place. Close to Gordano, the unlovely services recently renamed Michaelwood, here the views tell of the working life of the Severn and its confluence with Avonmouth. Docks and heavy industry sit on the muddy banks, and the temptation is to push the accelerator down a little further, and pick up extra speed to leave the litter strewn verges behind.On October 5th, 2009 workmen were carrying out maintenance here along the northwards side of the M5, clearing the undergrowth, when they came across some thin, cheap black plastic bin bags, tied across the top with building twine. Inside were bones and a skull. After thirteen years of fear over what had happened to Melanie Hall, the worst news was confirmed. These were the remains of her body. Although she had officially been declared dead, five years earlier in 2004, hope remained in her family that, by some miraculous chance, their daughter might turn up alive one day. That painful desire was wiped out by the discovery of those carelessly discarded bin bags.The question remains...Who killed Melanie Hall?