On New Earth, the entire population is trapped on an endless motorway with vehicles going around and around in circles for years. There is something far more serious to worry about than toxic fumes. Cars go missing on the fast lane of the motorway, never to be seen again, and there is something lurking at the bottom of the motorway, hidden beneath the fumes, something just waiting. Cast David Tennant (The Doctor), Freema Agyeman (Martha Jones), Ardal O'Hanlon (Brannigan) Anna