With the volume of traffic using Britain's congested roads increasing and the number of cops who patrol the motorways being cut, the police find themselves under pressure like never before. In the Midlands, the hub of Britain's road network, the motorway cops have switched from dishing out tickets and helping stranded motorists to concentrate on catching travelling criminals - car thieves and burglars who use the motorways to travel quickly and easily across the country. The M6 around Birmingham is Britain's busiest motorway interchange, but even here the search for criminals sometimes has to be put to one side when something more serious occurs. Torrential rainfall in the Midlands has flooded the motorway network, bringing it to a grinding halt, just when the summer holiday season has begun in earnest. With the tailback of cars, vans and lorries stretching for more than 35 miles, thousands of motorists will be forced to spend a cold and uncomfortable night in their cars unless the motorway cops can get them moving again. As their search and rescue mission gets underway, however, the cops come across some unusual and illegal behaviour.