Kate Humble follows the path of the ancient frankincense trade route through one of the most enigmatic nations on Earth - the Kingdom of Saudi Arabia. With unprecedented access, Kate enters the world of the nation's richest man, meets a remote mountain tribe whose ancestors once guarded the trade routes and who live at the fringe of Saudi society today, and explores the treasures of an untouched shipwreck that once carried frankincense on the crystal-clear waters of the Red Sea. Travelling by camel, glider and boat, she traces the 1,000-mile trail through the Kingdom and discovers the modern nation and its people.