“The Maltese Falcon” is a hard-boiled detective novel by former Pinkerton operative Dashiell Hammett. It was made into a movie of the same name by John Huston, then a first-time director. And as fans of the book and the movie know, the Maltese Falcon itself was the treasure sought by competing criminal elements who were ultimately thwarted by detective Sam Spade.

In Mr. Hammett’s 1930 novel, the detective story achieved the level of literature. And Mr. Huston’s B-picture became a classic of American film noir. (It didn’t hurt that Mr. Huston was able to hire Humphrey Bogart to play Sam Spade.)

This week, a lead statuette of the Maltese Falcon used in the movie became a bona fide treasure, selling at auction for a staggering $4 million. That sale, to an unidentified buyer, was more than 10 times the budget of Mr. Huston’s 1941 movie.

For comparison, another movie icon — Dorothy’s bejeweled ruby slippers from “The Wizard of Oz” — failed to sell for the minimum bid of $2 million in an auction in 2011.

In the book and movie, obsessed collector Kasper Gutman (played by the portly Sidney Greenstreet) declares, “There’s only one Maltese Falcon.”

Actually, two statuettes were cast to use in the film. So there is another lucky owner out there.

But indisputably, the falcon is still, as Mr. Spade put it, “the stuff that dreams are made of.” At least it has to be for the fan who paid $4 million to buy a movie prop made of 45 pounds of lead.