Not content to leave the field to former rock stars, sci-fi novelist Terry Pratchett is turning his hand to musicals. Pratchett has reportedly been drafted in as a consultant on the Theatre Royal Plymouth's co-production of Only You Can Save Mankind, the first instalment in Pratchett's Johnny Maxwell series. Though plays based on Pratchett's Discworld fantasies have proved popular with am-dram societies, the man is not known for his stage accomplishments but rather for being one of the country's most successful novelists - his books have sold an estimated 23 million worldwide and attracted a fanatical following. The stage adaptation of Only You Can Save Mankind will feature music by 23-year-old composer Leighton James House and lyrics by La Cava's Shaun McKenna. It will be directed by Jonathan Butterell, with musical supervision by Martin Koch. The show, with a cast of 14, is expected to premiere in Plymouth some time next spring.