The TV presenter continues his travels along the world's most challenging railways, setting out to reach the northernmost railway station on Earth, inside Russia's Arctic Circle. This is an epic 2,000-mile adventure from Moscow into Arctic Siberia, and begins with a marathon 19-hour leg. Along the way he enjoys a reindeer stew with a local family and takes the controls of one of the massive locomotives that power the trains, before pressing on along railways built under the brutal regime of Joseph Stalin.

• Chris Tarrant