When scoping the cuties at Van Pelt turns up, well, no cuties, pull your top hat low, trench coat tight, and head down to Whodunit - Philly's only mystery bookstore - to brush up on your detective work.

Around since 1976, Whodunit's shelves are stuffed with everything you need to get back in the game as a more suave and discerning incarnation of your former self: volumes upon volumes of Sherlock Holmes and The Hardy Boys. "We have the illustrated Sherlock Holmes, the annotated Sherlock Holmes, the complete collection of Sherlock Holmes," explains co-manager George Zippellin, stopping to examine a collection of scholarly essays on Sir Arthur Conan Doyle's creation.

Inspired by a famous New York-based mystery store after burning out in Philly's insurance industry, Whodunit owner Art Bourgeau decided to take his love for mystery novels full-time. And now, he claims Whodunit is the oldest mystery bookstore still operated by its original owner. While generations of mystery fanatics have kept the store going over the years, competition from online booksellers forced Bourgeau to expand its selection. Now, history, art theory, literature and philosophy sections draw in a mix of college students and urban intellectuals along with regulars. Take, for example, the petite, elderly Miss Marple-type who looked up from her investigations in the new mysteries section briefly last Saturday afternoon to declare, "Oh! I've been coming here for years!"

But, "it's [also] not unusual to find kids coming in and discussing John Dos Passos at two in the afternoon," Bourgeau said. Alongside the Marple was Carlos Carter, a young professional from Mount Airy. "I just like old mysteries. I like to look at the archives they have," he said before moving on to the African American studies section, which the owners say has become increasingly popular.

The left side of the store is dedicated to mystery, where in addition to classics from Conan Doyle and Agatha Christie (enough Christie, in fact, to liven up a year's worth of tea parties) are more modern thrillers from writers like Michael Crichton. Some of the store's other sections, however, are tougher to navigate, and faded binding on older books would be more easily read with the aid of a large, Holmes-style magnifying glass. Stuffed between volumes on Zen and the beginning of Christianity, one spies Mary Shelley's Frankenstein. A few books to the left sits a thick volume titled Japanese Manufacturing in the 20th century.

Other sections, such as architecture, art history and sociology aren't clearly marked, but do have some nice offerings - a biography of Van Gogh and a textbook on classical architecture with full-color prints. While other bookstores, like longtime Philadelphia staple Leary's, have caved under competition from national chains, Bourgeau says that he's tried to carry inventory that no other bookstores would stock - like history dissertations and Norman Mailer's lesser-known books. There are even books on the integration of Moroccan Jews into Israel and a thick tome on economic theory. "What we're looking to buy is the more obscure, the more esoteric, the more specific," he said.

At Whodunit, the biggest mystery of all may be figuring out when to drop by. "Normally we close at 6:30," Zippellin said. "But it looks like it's going to be a nice evening"