The séances have been held — unsuccessfully, we should add — ever year since Houdini died on Halloween day in 1926. The cause of death was peritonitis, or a rupture of his appendix, a condition Houdini developed — or so popular history goes — after a college student went backstage and sucker-punched him in the gut. Each year on the anniversary of his death, Houdini-heads and magic maven have huddled around a medium. Then she calls his name — Harry, Harry, Harry — and asks, then begs, him to return. He doesn't.

This year, however, the stakes are raised, if only so he can mumble a few words to set the record straight. A new book, The Secret Life of Houdini, claims he was not only a spy, working for American intelligence agency and Scotland Yard (he allegedly spied on Germany for the Brits, along with monitoring anarchists in Russia), but also that he was poisoned by rivals.

Authors William Kalush, an amateur magician who runs the Conjuring Arts Research Center here in New York, and Larry Sloman, who collaborated with Howard Stern on Private Parts, spent a decade cobbling together research materials and pouring through millions of documents to state their claims. Their big break came at a Houdini séance when they met Anna Thurlow, the great-granddaughter of Houdini's nemesis, the medium Margery. Thurlow led them to a closet in her Long Island home filled with never-before-seen correspondence between Margery's husband, Leroy Crandon, and Conan Doyle, the Sherlock Holmes author. Thurlow thinks it's possible her ancestors were behind Houdini's death.

At the time he died, Houdini was trying to expose Margery and Crandon, a doctor who specialized in the appendix, and their fellow spiritualists as frauds. "There's certainly a lot of circumstantial evidence that they did not wish Houdini well," Thurlow says. "My great-grandfather was not a nice man."

But not-nice enough to murder Houdini? At noon today, on West 16th Street, perhaps we'll find out.

— Geoffrey Gray