This is the story of what first led Benedict Allen to head for the farthest reaches of our planet - at a time when there were still valleys and ranges known only to the remote communities who inhabited them. It is also the story of why, thirty years later, he is still exploring. Benedict decides to journey back to a clouded mountain in New Guinea to find an old friend called Korsai, and to fulfil a promise they made as young men.

Explorer tells the story of what it means to be 'lost' and 'found'.