Later this year, the celebrated Australian director Peter Weir will release his latest film. Titled "The Way Back" it is based on a book which has puzzled the world for 50 years. In 1956, a Polish officer called Slavomir Rawicz caused a sensation with "The Long Walk," his account of a his dramatic escape from the Soviet Gulag and a 4000-mile trek on foot to India. The book was a bestseller and has remained in print for over half a century. Rawicz describes how he his fellow escapees slogged across the Siberian tundra, traversed the Gobi Desert and scaled the Himalayas. Along the way they faced hunger, exhaustion, disease and even a couple of yetis. A thrilling story: but was it true? Many have doubted whether this extraordinary tale can really have happened. Four years ago, Tim Whewell investigated for a Radio 4 documentary and discovered evidence that decisively proved whether Rawicz really made his amazing journey. Now there's further evidence which adds another twist to the tale - including a meeting with the man who might really have made this epic trek. This updated version of the programme proves once again that truth is truly stranger than fiction. Producer: Hugh Levinson.