At night, a lorry jack-knifes on an unlit section of the M6, and two cars have ploughed full-speed into the underside of its trailer. The roofs of both cars have been taken off in the impact, and one man is dead. But, miraculously, three others have survived. It's up to PCs Elliot, Bullard and Shail to find out if this was simply the hand of fate or if someone is to blame.

• Jamie Theakston