Sky + set.
Synopsis from the BBC:
The coldest winter for thirty years brings chaos on the roads, causing tailbacks and crashes as drivers ignore the signs to slow down. On the M6 a hit and run driver causes a three car pile-up, and the Motorway Cops are forced to close the motorway to deal with the injured, before turning their attention to finding the motorist who was the cause of it all.
In the city centre, the race is on to help more than 40 school children stranded in a broken-down bus in the middle of 6 lanes of fast-moving traffic. Meanwhile, PCs Smith and Westbury attempt to track down a wanted man, but instead find two young children home alone, and are forced to take them into temporary police care.
As the winter weather worsens, the bumps and crashes on the M6 become more frequent, stretching the team to the limit, but it's a night-time call out to a car driving the wrong way down the snow-covered M42 which takes priority.