JK Rowling has written a prequel to Harry Potter.
The story, which is shrouded in secrecy, was penned in the past month and is just 800 words long.
Her Potter prequel comes almost a year after the last book in the boy-wizard series, 'Harry Potter and the Deathly Hallows', hit the shelves.
The latest tale will not be published but sold at a charity auction next month instead.
Organisers asked 13 authors, including Margaret Atwood, Sebastian Faulks, Nick Hornby and Doris Lessing, to create a story for the sale.
The celebrated writers could submit anything from a doodle and collage to a fresh story.
Organisers were amazed when JK Rowling handed over a prequel to the Potter series, which sold more than 375 million books worldwide.
JK Rowling, who has earned a £560m (€708m) fortune from the seven Potter stories, is determined the latest instalment will not be developed further.
She says at the end of the story, written on both sides of an A5 storycard: “From the prequel I am not working on – but that was fun!”
JK Rowling, whose books have also been turned into a series of record-breaking films, said in 2007 that if she did write another Potter tale, it would not be for another 10 years.
Philip Errington, a specialist at Sotheby’s, which will run the auction, said the 13 storycards will be sold without reserve prices.
He said: “Given the enormous interest we have seen in recent times for autograph work by JK Rowling, the prospects for her storycard are good to say the least. There is just no telling how high the bidding might go.”
Waterstone’s Managing Director Gerry Johnson said: “We never dreamed that JK Rowling would donate something so precious.”
Money raised from the sale will go to English PEN, which promotes understanding through literature, and Dyslexia Action.
Faulks has written a story of “desire and obsession” in a “classically-inspired erotic tale”, Irvine Welsh a tale of a “taciturn oil rig worker at odds with his lot”, Nick Hornby introduces odd superhero, 'Nightburner', in a mixture of collage and text, and Tom Stoppard a theatrical short mystery.
In December last year, a new JK Rowling work, 'The Tales of Beedle the Bard', fetched £1.95m (€2.5m) at auction.
The auction will be held at Waterstone’s in Piccadilly, London, on June 10.
All the stories will be published together in a special book to mark the auction.