The Third Man Factor by John Geiger Canongate, HK$185

In 1922 T.S. Eliot wrote in The Waste Land: 'Who is the third who walks always beside you? When I count, there are only you and I together.' That poem was inspired by an Antarctic expedition: Ernest Shackleton had recounted how, nearing an endurance cut-off point, he and his climbing mates had felt a presence infused with spiritual significance that urged them on. This was the Third Man of John Geiger's book, which investigates the phenomenon that others - prisoners of war, Vietnamese boat people, survivors of mine disasters - have described with uncanny similarity. Some refer to this entity as their guardian angel; others try to explain it with science. In his chapter The Pathology of Boredom, Geiger says hallucination may occur as a result of 'the effects of exposure for prolonged periods to a rigidly monotonous environment'. Other possible explanations are appended to story after story of people who, nearing their last gasp, are joined by a benevolent being. That was also the experience of Ron DiFrancesco, apparently the last man out of the south tower of the World Trade Centre on September 11, 2001, who remembered being 'lifted' up.