The site received more than 70,000 visitors in the first 20 hours of Rowling's story going live online last week and has been getting thousands more hits daily from fans keen to read Rowling's 800-word prequel to the Harry Potter series, making it Waterstone's most successful online campaign yet. The competition has attracted nearly 4000 story cards so far. JK Rowling's story is set three years before Harry is born and features the characters Sirius Black and James Potter, Harry's father. The story opens with a youthful Sirius and James cornered by two irate policemen at the end of a high-speed motorcycle chase. After a cheeky exchange with the policemen, the two teenage characters make their escape - using broomsticks, "drumsticks" and just a little bit of magic. JK Rowling's exclusive short story is one of a number of stories that were auctioned off at Sotherby's, raising more than £47K for charity, as part of Waterstone's What's Your Story? competition. The Harry Potter prequel raised £25K alone. Bespoke stories written by the top authors especially for the promotion are being displayed in an online gallery, in store windows and will be published in a limited edition book. Waterstone's promotion is searching for budding writers to be published alongside JK Rowling, Doris Lessing, Michael Rosen, Nick Hornby, Sebastian Faulks, Lauren Child, Tom Stoppard and Irvine Welsh. To be in with a chance of winning people simply submit their story that can be from three words long to three hundred - just as long as it fits onto the story card template. This latest promotion follows the success of Waterstone's Save Harry Potter online petition that achieved more than 500,000 signatures last year. Code Computerlove has worked as Waterstone's retained digital agency for the past two years. It is responsible for the Waterstone's website www.waterstones.com as well as promotional sites.