For the 1941 John Huston film adaptation of Dashiell Hammett's San Francisco-set noir novel The Maltese Falcon, a book twice produced as a film before this defining version starring Humphrey Bogart as the tale's hardboiled private eye Sam Spade, Huston may have had several prop falcons made.

One of them has been prized more highly than others, marketed as the original. Known as the Milan Falcon for its longtime owner, a Los Angeles oral surgeon named Gary Milan, Bonham's sold the prop for a record $4 million in 2013. Fewer know that another falcon with a similar claim was also sold in 2013, though it fetched far less. This week, on the 75th anniversary of the film's theatrical release, an article in Vanity Fair pries deeper into the story of the prop and its potential siblings — legitimate and illegitimate. While not as suspenseful as Hammett's original tale, in which the falcon is supposedly filled with treasure, the story of the famous Hollywood prop is similarly an interesting study in MacGuffins — objects whose idea matters more than their reality, driving people and plots with their mysterious power.

On the anniversary of The Maltese Falcon's release yesterday, the Hollywood Reporter republished their original 1941 review:

Another prize package from Warners, The Maltese Falcon is going to be one of the most profitable and talked about pictures of the year. On a number of accounts it is distinguished celluloid entertainment, but it is of great interest to the trade because it reveals, in startling terms, the unheralded talent of topflight scenarist, John Huston, who, in the dual capacity of writer and director of this picture, is now entitled to take his place among the most important creative artists in the industry.

The anniversary was also seemingly the news peg for the Vanity Fair article. The Milan falcon, Vanity Fair writes, was "lost to history for decades" then resurfaced in the 1980s in the hands of a Beverly Hills oral surgeon, and beginning in 1991 traveled the world as part of a Warner Bros." When it was sold at Bonhams’s Madison Avenue showroom. "Spectators gasped as a bidder in the audience dueled with one on the telephone, driving the price higher and higher." The winning bid went to the Las Vegas hotel and casino billionaire Steve Wynn. But "it turns out there is another, far stranger version" of the story, according to the article, "and another Falcon... several more in fact."

When asked, in the film, what the falcon is, Sam Spade tells a cop that it's “The stuff that dreams are made of.” Actually it's made of lead according to Milan, though Spade's answer is more poetic. In fact, the Milan falcon was supposedly dropped on Humphrey Bogart's foot during filming, bruising the soft metal feathers and leaving an imprint on its tail that conferred its veracity.

Not convinced there was just one falcon — and doubtful there would have been one made of lead, even if it's supposed to be lead in the story — is a man named Hank Risan who says he's got two falcons made of plaster that were also used in filming. On his side are a UCLA film professor and former head of the United States Copyright Office. Confusion in the story comes from the fact that replicas of the original falcon, or falcons, were made for the 1975 satire film with George Segal called The Black Bird. But Risan and experts have noticed a weird marking on his two falcons: “7.5.,” it seemed to read. Eventually, Risan decoded that as FS, the initials of Fred Sexton, a friend of Huston's and an artist. Risan even tracked down Sexton's daughter, who recalled her father making the sculpture and even being on set herself as a nine-year-old.

The Vanity Fair article's findings are these:

In all, there appear to have been at least six plaster Falcons created for the 1941 movie, an assertion first made in a little-noticed 1983 memoir by a onetime Warner employee named Stuart Jerome. One is thought to have been damaged, then destroyed, during filming in 1941. By this count, Risan owns Falcons two and three; he sold four, to a buyer who declines to be identified. According to an article in a U.S. Copyright Office newsletter, Warner Bros. gave a fifth Falcon to the Copyright Office for an exhibition in 1984. The article says one more plaster Falcon, the sixth by this count, was still in the Warner warehouse at the time. During the course of research for this article, I spoke to a credible individual who said he had recently seen this Falcon — of unpainted plaster — in the warehouse.

Laura Woolley, a Hollywood appraiser and "professional skeptic" is the clearest voice in all this mystery surrounding the prop. “I don’t understand why anyone would make a lead bird,” she told Vanity Fair. “You don’t cast in lead. But Warner’s believes in it. Gary [Milan] believes in it. So it’s kind of become the official bird.... [Lead] only makes sense if you wanted something that appears very heavy. If it’s supposedly something that contains treasure inside, you should be holding it as something quite weighty, and that’s the only reason you could ever do it in lead. Maybe they dropped it on Bogart’s toe and went to plaster instead. Who knows?”

Spoiler alert: There's little that's conclusive in the film of The Maltese Falcon, but it's downright satisfying compared to the looser ending of Hammett's book. But if you were looking for finality in a MacGuffin story itself about another famous MacGuffin story, sorry pal, as Sam Spade might put it. "It’s a shame to end this story on an ambiguous note, but it’s much the same ending that Hammett wrote for his novel and John Huston shot for his movie," Vanity Fair explains. "Sam Spade remained in foggy San Francisco, Kasper Gutman headed to Istanbul, and the mystery of the Maltese Falcon lived on, unsolved."

These days seekers of all kinds don't need to head to Bonham's or the office of a private eye to get their falcon fix. Amazon.com sells a very convincing replica for just $185 — it even comes, true to the tale, "Wrapped in Chinese Newspaper, Bound with Twine in Captain Jacobi’s La Paloma Burlap Sea Bag."

Related: The 14 Best San Francisco-Set Novels