A bad fall and more mechanical trouble dogs Ewan McGregor and Charley Boorman as their motorbike odyssey continues. After regrouping to assess the damage, they head for Ulan Bator and are taken on an underground tour of the Mongolian capital's sewers. They then travel back into Russia and on to Siberia, where they're informed of a really bad stretch of road ahead. Reluctantly they decide to let a train take the strain.