Terry Pratchett is one of the most loved writers in the world. With worldwide sales of over 65 million copies in 37 languages, his novels are eagerly awaited by his legions of fans year after year. His first Discworld novel, The Colour of Magic, was released in 1983 and ever since then the series, with its whimsical heroes and fiendish foes, has delighted both young and old alike. In 2007 Pratchett announced that he had been diagnosed with Alzheimer's...