"The prequel, set shortly before the birth of Harry Potter, centres on his father, James, and his mentor, Sirius Black".
More than 450 million copies of the seven original Harry Potter books have been sold worldwide in 79 languages.
The manuscript was stolen during a break-in between April 13 and 24, West Midlands Police said.
Author J.K.Rowling and West Midlands Police in England are experiencing a serious case of expelliarmus today, with authorities and Rowling calling on fans to help them locate a missing untitled "Harry Potter" prequel.
"We are appealing to anyone who sees, or is offered this item for sale, to contact police", he said. Through her very popular Twitter account, the author shares much of herself with fans (while also shutting down trolls on the reg), and often gives out little tidbits of HP information (like her huge Fantastic Beasts 2 hint).
British police are searching for the Muggles who stole a rare and valuable "Harry Potter" prequel.
Some Harry Potter fans had fun with the news, and came up with innovative responses to Rowling's pleas.
The work was auctioned off nine years ago and sold for £25,000. In November 2018, the second installment of the five-part franchise, starring Jude Law as Hogwarts headmaster Albus Dumbledore and Johnny Depp as Gellert Grindelwald, will be released.
Until now, Potter fans did not know that a prequel story existed.
Admitting it can be a useful took, she went on to tell the Telegraph: "The aim of my novels isn't to tell people what to think or to tell them how I think, it's to get the conversation going".