The atlas of 1816 was littered with blanks. What was the North Pole? Was there a Northwest Passage? What lay at the heart of Africa? Did Antarctica exist? In his quest to find the answers to these questions, John Barrow, Second Secretary to the Admiralty, launched the most ambitious programme of exploration the world had ever seen. Between 1816 and 1845 his hand-picked teams of elite naval officers scoured the globe’s empty spaces. Often at odds with each other and working in utterly surreal conditions – cocked hats in the Arctic, frock coats in the Sahara – they entered the void. Their ignorance of the conditions they would encounter, allied to Barrow’s insouciant way with maps, make this a tale of absurdly dangerous comedy as well as harrowing personal endeavour.