Unless you have just returned from a long incarceration on the Gulag Archipelago, you already know that J.K. Rowling has ended her 17-year relationship with Harry Potter, telling her countless readers that it’s over and she never wants to see him again. It’s a crushing blow for those who loved them both, but at least she didn’t kill him (well, probably not, anyway).

Harry might never be seen again, but the good news is that Ms. Rowling’s next book will be a detective novel. Her friend and neighbor in Edinburgh Ian Rankin, the most successful mystery writer in the British Isles, spilled the information to England’s Sunday Times at a literary festival in his hometown.

Mr. Rankin’s wife, Miranda, appears to have looked over the shoulder of Ms. Rowling while she was tapping away on her laptop in a café, where she famously began her writing career — first out of necessity, the impoverished single mother needing to save on heating bills at home, then out of preference. If her detective fiction is anywhere near as successful as her magical fantasy novels, she could challenge Agatha Christie as the most successful mystery writer of all time.

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Speaking of Christie, her work will now appear in comic book form in an attempt to appeal to a new generation of young readers. The series launches in England next month to coincide with the annual Agatha Christie Week (September 9th to the 15th). Twelve titles, beginning with “Murder on the Orient Express,” will be released immediately, with 83 scheduled for future publication.

According to the “Guinness Book of World Records,” more than 1 billion copies of Christie’s books have been sold; only William Shakespeare has been more widely read (and he had a head start of more than three centuries).

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The mystery community of New York, and book lovers everywhere, will be dealt another blow when the Upper East Side’s much loved Black Orchid book store permanently closes its doors this Friday. The cozy little shop tucked into East 81st Street was a neighborhood gathering place for mystery fans for 13 years, and its many friends have only warm wishes for proprietors Bonnie Claeson and Joe Guglielmelli.

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The Detroit Tigers, in the middle of a tight pennant race, have signed up some help. Elmore “Dutch” Leonard was given a contract as the team’s designated writer and dialogue coach, which should help make interviews with the players a little more exciting than hearing that they’ll “take it one game at a time” and “give it 110%.”

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Sometimes, good books have bad titles, and Barry Forshaw’s “The Rough Guide to Crime Fiction” (Rough Guides, 320 pages, $12.99) is one of them.

This handsome, intelligent, and honest handbook has the ring of a book that will cover only hardboiled stories, thug lit, and excessively violent adventures of drug abusers and other forms of lowlife. But instead it’s a fair overview of all the mystery fiction genres, with pretty good taste.

“The Rough Guide” makes no attempt to be comprehensive, focusing instead on the better authors and their best books, which is what most readers want or need. In addition to covering most major contemporary writers, Mr. Forshaw, who reviews crime and other fiction for several major English newspapers, provides little biographies of the top figures, as well as lists their five best books, which is where many readers (including a pedant like me) will find reason to object.

Selecting Ian Rankin’s “Knots and Crosses” as his best book, for example, suggests that Mr. Forshaw didn’t read it, or that his memory has been dimmed by the excessive consumption of alcohol or cookies or equally toxic substances. While the John Rebus books of Mr. Rankin (who supplied a brief foreword) are among my favorite detective stories, that first one was, as the author himself acknowledges, a stinker.

But that is the nature of lists, and anyone who publishes them is both brave and foolhardy. Maybe a forthcoming column will list my all-time favorite lists.

Mr. Penzler is the proprietor of the Mysterious Bookshop in Manhattan and the series editor of the annual “Best American Mystery Stories.” He can be reached at ottopenzler@mysteriousbookshop.com.