At 5.15 p.m. Harvey Ellis was trapped - stranded in a line of eight cars by a blizzard on a Norfolk coast road.

At 8.15 p.m. Harvey Ellis was dead - viciously stabbed at the wheel of his truck.

And his killer has achieved the impossible: striking without being seen, and without leaving a single footprint in the snow . . .

For DI Peter Shaw and DS George Valentine it's only the start of an infuriating investigation. The crime scene is melting, the murderer has vanished, the witnesses are dropping like flies. And the body count is on the rise . . .