Stephen Colbert must alter his Christmas plans when he's trapped in his upstate New York cabin by a bear, but he manages to get by with a little help.

Jonas and the team must travel through enemy territory to bring a young bride to her groom, preserving a truce between two warring Afghanistan tribes; Kim and Bob try to expose a man who is linked to terrorists.

Jeremy, Richard and James are challenged to drive from the heart of Switzerland to the north-western coast of England on just one tank of fuel, with the winner switching on the Blackpool illuminations. James also power tests the Pagani Zonda F Roadster, and the Stig sets a lap time in the Bugatti Veyron. Grand Designs presenter Harry Enfield is the Star in a Reasonably Priced Car.