On 19 December, a crossover accident on the M25 motorway in Surrey involving several vehicles forces Inspector Clive Turner, head of the police unit with jurisdiction over the M25, to close the motorway in both directions from the site of the accident. The resulting traffic congestion spreads at such a rate that, within minutes, the motorway is blocked at the junction with the M23. Meanwhile, as British airspace runs over capacity to cope with the Christmas traffic, heavy traffic delays force the air traffic controllers to work double- and triple-shifts. Meanwhile, Julian Galt and his family are travelling into central London en route to Heathrow Airport, for their Christmas holiday to Bilbao, with their twelve-year-old son recording their adventures on a video camera.