Simon Reeve continues his epic journey around the world following the Tropic of Cancer, the northern border of the tropics region.

The second leg of the journey sees Simon dodge the Moroccan secret police in Western Sahara, travel on one of the world's longest trains in Mauritania, visit a forgotten refugee camp in the Algerian desert where more than 100,000 people live, and take a swim in a Libyan oasis with a government minder who bears an uncanny resemblance to Colonel Gaddafi.

After travelling around the Tropic of Capricorn and the Equator, this series completes Simon's trilogy of journeys exploring the amazing tropics region with his toughest, longest, most ambitious challenge yet.