(CNN) An untitled prequel to the wildly popular Harry Potter books has been stolen in a robbery in the UK, authorities say.

Just 800 words long, the handwritten manuscript -- written on two sides of an A5 postcard by author J.K. Rowling -- was taken from a property in Kings Heath, Birmingham.

The short story was previously auctioned off for charity in 2008.

"The only people who will buy this unique piece are true Harry Potter fans. We are appealing to anyone who sees, or is offered this item for sale, to contact police," investigating officer Paul Jauncey said in a statement

We are asking #HarryPotter fans to help share our appeal after a rare Harry Potter prequel by @jk_rowling was stolen https://t.co/NLH79kAoLf — West Midlands Police (@WMPolice) May 12, 2017

The story is said to feature a young James Potter, the titular boy wizard's father, and his best friend Sirius Black, who come across two "muggle" (or non-magic) policemen following a high-speed chase, according to local media reports.

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