Perhaps the most conclusive evidence of anti-Semitism's enduring appeal for conspiracy theorists came in the aftermath of al-Qaeda's September 11 assault on the United States. Although it was non-Jews who masterminded, executed and proudly claimed credit for the mass killings, depressingly little time passed before rumors began to circulate that it was Jews or Israel, not Islamic terrorists, who were behind the attacks. Those rumors, repeated not long afterwards to filmmaker Marc Levin by a New York City cab driver, serve as the basis for Protocols of Zion, an HBO documentary airing tonight at 10p.m. on HOT Prime. Though it occasionally loses focus, the 90-minute film provides a thought-provoking look at contemporary anti-Semitism, and the delusional conspiracy theories that continue to exert a hold on millions around the world. Levin's film draws its name, of course, from The Protocols of the Elders of Zion, the purported minutes of a meeting between Jews conspiring for world domination. Themselves the product of an anti-Jewish conspiracy - the Protocols are believed to have been forged by the secret police in czarist Russia - they've been debunked at least six times since 1921, when The Times of London published the first report revealing them as a fraud. With their rather unsubtle portrayal of the Jewish conspirators - who utter lines like, "From us emanates all evil" - the Protocols would seem to discredit themselves even among the most ardent and gullible anti-Semites. But the book has proven remarkably durable and persuasive, Levin says, noting that the Protocols have made the technological leap to the Internet and Arabic satellite TV, where they've been adapted for film and screened for massive audiences across the Arab world. In many cases, the documentary suggests, the Protocols merely attract the readership of those looking to reinforce preexisting views about Jewish greed and treachery. At one point, Levin encounters a small group of black radicals, who knowledgeably inform the filmmaker that Pepsi donates 33 cents from every purchase to Israel, and that even powerful figures who don't appear Jewish actually have nefarious Jewish connections. "Giuliani?" one of them says in mocking reference to New York City's mayor on September 11. Clarification: that's "Jew-liani." Similarly disturbing is a member of the National Alliance, a white supremacist group, who calls the Protocols "timeless" and disseminates it along with Nazi propaganda films. The editor of an Arab-American newspaper in New Jersey explains that he reprinted the Protocols after September 11 to expose them as an anti-Jewish fraud, then immediately attributes their popularity to people who "are jealous because the Jews control everything." While all of this is disturbing, it isn't exactly surprising. (A white supremacist who doesn't like Jews? You're joking.) More interesting are the moments when Levin deals with aspects of the Protocols' history that are less well-known, such as their importation to the United States in 1920 by automaker Henry Ford, who gave away free copies to buyers of his cars. A Muslim man in New Jersey shouts at Levin - justifiably - for having found only the most ignorant possible Arab-American youths to interview for his film, then gives away his own biases when he claims that it's exclusively Arabs, not Muslims in general, who spread Jewish conspiracy rumors in the period after September 11. Indeed, Protocols of Zion is at its best when it gets specific about the recent resurgence of the Protocols and other Jewish conspiracy theories. While he can't say with certainty where the number 4,000 came from - that's the number of Jews who were supposedly tipped off to stay at home on September 11 and thereby avoid death - one of the film's experts recalls a television appearance by Israel's consul-general in New York, during which the consul described the 4,000 phone calls he'd received from anguished Israelis inquiring about relatives feared dead in the attacks. According to Levin, reports about the 4,000 mythical Jews made headlines in Turkey and gained widespread currency among German youth, leading to upsetting questions about the rumors' ability to spread beyond the actively anti-Semitic fringe. (In actuality, it's estimated that several hundred Jews died during the September 11 attacks.) While frequently compelling, Protocols of Zion also tends to wander off course, including in self-indulgent and disconnected sections devoted to Levin's own family. The director also errs lazily in asserting that "nothing has done more" to create new Protocols believers than the second intifada. A new generation may find itself critical of Israel's policies, yes, but what makes the acceptance of a delusional forgery the next logical step? Levin never substantiates the claim, and settles elsewhere on arguments that come across as simplistic or unsupported. Whatever its shortcomings, however, Protocols of Zion is a thought-provoking film, one whose questions will linger even after viewers have forgotten the insufficient answers it provides.