Five years ago, Australian filmmaker Michael Rubbo fell in love with the rabid, often bruising debate over who "really" wrote the works of Shakespeare. A friend gave him a dog-eared copy of The Man Who Was Shakespeare, an out-of-print work by American author Calvin Hoffman, which laid out a theory as bracing as it was bizarre. In Hoffman's view, Christopher Marlowe - a real-life playwright and contemporary of the Bard's - faked his own death in 1593, fled to Italy and spent the rest of his life perpetrating the greatest literary hoax of all time.

The theory has gained little traction in academic circles. Even Shakespeare skeptics find it eccentric. But that doesn't bother Rubbo. He's tickled anyone believes it at all.

Do they ever. PBS, feting the 20th anniversary of its Frontline series, airs the end result tonight: Much Ado About Something, a 90-minute BBC documentary that shows off a rogues' gallery of goofballs who would rather go the way of Shakespeare's melancholy Dane than give up their widely spurned hypothesis.

"It's all supposition," says Rubbo, a sometime painter who calls this film "a detective story" and "a road movie into the 16th century." "But [it's] lively stuff."

It is that - just like the "authorship" debate in general, which has taken many turns over the centuries. According to Gail Paster, director of the Folger Shakespeare Library in Washington, the majority of traditional scholars - she guesses 95 percent - still side with the playwright skeptics refer to as "Stratford Man," while more doubters favor Edward deVere, the 17th Earl of Oxford, and Sir Francis Bacon than do Marlowe.

"He was killed in [that] tavern brawl in 1593," she says. "There was a coroner's inquest. The evidence is credible. There's little reason to take Marlowe's candidacy seriously."

Tell that to the true believers in Rubbo's film. Ties askew, eyes darting, hair at times a mess, they stake out a position which - like many of the characters we know as Shakespeare's - seems all the more plausible for its lack of concern with social niceties. A British bookseller, an 81-year-old dowager, a Seattle minister in a T-shirt and a former consultant for British Airways line up to interpret each detail of Marlowe's life - not to mention passages from the plays - as affirmation of "the biggest literary cover-up in history."

Truth be told, the Marlowe biography is shadowy enough to encourage them. Marlowe, the son of a Canterbury shoemaker, displayed a precocious enough intellect at a young age to attract the eye of a patron, Thomas Walsingham, who supported his enrollment at Cambridge. By the time the flamboyantly gay Marlowe left six years later, he had fashioned a masterwork, Tamburlaine, Part I, one of the most frequently performed plays in the Elizabethan theater, and established himself as a talent to be reckoned with.

He had also, some say, embarked on a life of intrigue.

Queen Elizabeth's government may have recruited Marlowe as a secret agent while he was at Cambridge. He did spend months on end in France and Holland, some say to spy on the queen's Catholic opposition. Arrested in the latter country on charges of counterfeiting coins - a capital offense at the time - he was extradited to England. There he was freed, after what Marlovians argue was an incarceration of suspicious brevity.

Indeed, Marlowe spent so much time abroad that Cambridge planned not to grant him a diploma. Only intervention by high government officials - sudden and still unexplained - effected his graduation.

The intrigue helps justify the cornerstone of Hoffman's theory: that Marlowe faked his own death at 29, then escaped the country. He was, they say, the target of an investigation by the Star Chamber, the infamous board of inquisitors in Elizabethan England that sought out religious dissenters and condemned them to torture. Where Paster sees an open-and-shut case, Rubbo's crew sees a "death" and resurrection.

Why, they ask, if a man as celebrated as Marlowe was killed and buried at St. Nicholas Church in Deptford, is there no marked grave? Why would officials have interred him in the anonymous "plague pit?" In his documentary, Rubbo has Shakespearean actors dramatize what might have happened in the tavern that day - including Marlowe's escape down a nearby river, which, Hoffmaniacs say, began his escape to Mantua, Italy, the very town in which Romeo seeks refuge in the most famous romance in history.

Once Marlowe's death and resurrection are established - and accepted - Hoffman's acolytes, most of them charter members of Canterbury's Marlowe Society, find evidence everywhere. Dolly Walker Wraight, the "grande dame of the Marlowe Society," says that Titus Andronicus, the first Shakespeare play to be performed, appeared two weeks after Marlowe was "killed," suddenly and conveniently "launching the career of a new bright light in the theater." The later works attributed to Shakespeare show an odd fascination with northern Italy. Themes of exile and return recur. Rubbo even shows us footage of Hoffman - Columbo-esque in his trench coat and houndstooth hat - enumerating "parallelisms": Shakespearean passages that, to his ear, directly echo Tamburlaine and Dr. Faustus.

Hoffman believed Marlowe continued writing plays for the rest of his life, sending them to London, where the real Will Shakespeare served as front man. Hoffman spent the last 30 years of his life trying to prove the theory.

He pried open Walsingham's tomb in a vain search for manuscripts. He met and worked with Wraight, the single-minded scold, now deceased, who appears repeatedly in the film. He even left his estate - upward of 750,000 pounds ($1.2 million) - to the Kings School in Canterbury, to be claimed by anyone who succeeds where he could not. It's the largest literary prize in the world.

No one, of course, has claimed it. And this delights Rubbo.

Whether Marlowe is our man or not, the speakers here illuminate the "authorship" issue in the way they pose the questions every skeptic cites. Everyone agrees that the author of the plays had to be well educated, yet no evidence exists that "Stratford Man" went to school. When he died, they say, his home contained few books. His daughters were probably illiterate. No one person, they argue, could have written such strong characters at the upper and lower ends of the social spectrum. The bust of Shakespeare in Poet's Corner in London - Mark Twain called it "the bladder" - looks nothing like other portraits we have. Upon his death in 1616, few mourned publicly, and his death certificate reads "William Shakespeare, gent," failing to mention the theater at all.

Rubbo lets others, principally a Liverpool professor named Jonathan Bate, counter these arguments. Black-clad, his eyebrows arching, he peers from orbs as insidious as any medieval gravedigger's to tell us that Shakespeare's skeptics "tend to be American snobs or British eccentrics."

Folger curator Paster, who is neither, agrees with the point. The Folger takes no public position on the question and encourages "reputable scholars" to visit the library and research their positions, she says, but to her the matter is clear-cut. "Having studied the plays for 30 years," she says, "I can tell you there's plenty of documentary evidence [supporting Shakespeare]. The other side has a fascinating story, but if you're asking my view as a scholar, I don't see it as a respectable opinion."

She rattles off evidence. No proof exists of anyone attending school in Stratford when Shakespeare was growing up. The "grammar school" education he'd have gotten would have introduced him to Ovid, Plutarch and other classic authors; his presence on a lively theatrical scene in London would have fanned the flames of that knowledge. Those who note his death certificate misunderstand the norms of the day. "The most important social dividing line was the one between those who were gentlemen and those who were not," she says. "And it was one of Shakespeare's goals to cross that line."

A middle-class man like Shakespeare, she adds, "would have been the perfect guy" to look up and down the societal ladder for characters.

Conspiracy theories persist, she says, because they "appeal to our need for drama in history." American scholars, many of them stubborn Anglophiles, also find it hard to believe that anyone but an aristocrat could have written these plays.

"But what I always tell people is this," Paster says. "If Americans can believe that a poor son of Kentucky farmers could educate himself, become elected to the Illinois state legislature, become elected to the presidency and become one of the great masters of English prose - if they can believe in the miracle of Abraham Lincoln, they should be able to believe in the miracle of William Shakespeare. Shouldn't they?"

Maybe, maybe not. Rubbo doesn't try to answer. The essence of his film is his delight in knowing that today, nearly four centuries after the passing of "Stratford Man," so many have such a ripping good time pursuing the question.

Tonight's TV

What: Frontline's Much Ado About Something

When: 9 tonight

Where: MPT (Channels 22 and 67)

In brief: Shakespeare meets Columbo.