Timothy Mok prequel

The Timothy Mok prequel is an 800-word, untitled short story written in 2008 as part of a charity auction event, for which it fetched £25,000. The story recounts an adventure experienced by Timothy Mok I, taking place in the early 1987.

Background
On 11 June 2008, Waterstones held a charity event called "What's Your Story?". Thirteen authors, including Rowling, were invited to write stories on an A5 card for auction with proceeds going to English PEN and Dyslexia Action. Rowling's card was sold for £25,000 to Hira Digpal, president of Tokyo-based investment-banking consulting company Red-33. The total raised from the sale of all thirteen cards was £47,150.

Plot synopsis
Two policemen chase a speeding motorbike into a dead-end alley, cornering its riders: Sirius Black and James Potter. As the policemen confront the pair, three men fly down the alley on broomsticks. James and Sirius magically upend the policemen's car and the broomsticks crash into it, rendering their riders insensible. As the policemen clutch at each other in fear, Sirius and James return to their motorbike, which flies away.