If you didn’t see “The Godfather,” or didn’t like it, read no further. But if “La Cosa Nostra” and “mafia” and names like “Sam the Plumber” and “Matty the Horse” stir your interest, you should read on.

Two decades after someone left it (presumably by accident) in a New York City taxi, a 3-inch thick, three-ring binder stamped “Mafia” and “United States Treasury Department Bureau of Narcotics” is going on sale on Wednesday at the New York branch of the famed British-based Bonhams ^[1] auction house, National Public Radio reported. ^[2] It’s expected to go for $10,000 to $15,000. (Isn’t that about what a run-of-the-mill “hit” cost in the good old days?)

“Only 50 copies of the file were thought to have been printed,” NPR reported. “The one for sale at Bonhams is No. 31, and the others were probably destroyed, said Christina Geiger, director of Bonhams New York fine books & manuscripts.”

Nicholas Pileggi, whose book “Wiseguy” was adapted for the movie “Goodfellas,” called the publication “a treasure trove for true-crime buffs and mob aficionados,” NPR said.

The file was compiled between 1957 and 1962 by the Bureau of Narcotics, forerunner of the Drug Enforcement Administration, NPR said. Robert F. Kennedy is believed to have used a copy while he was U.S. Attorney General in 1963 during hearings into organized crime.

Geiger said a cab passenger found the binder inside a black bag on the seat one night in the early 1990s after leaving Radio City Music Hall. “He basically just kept it to himself until contacting HarperCollins in 2006,” Geiger told NPR. “The owner, who is connected with the film and music industry in Hollywood, did not wish to be identified. “HarperCollins published a facsimile of the book a year later, with some sections redacted.”

Now, the complete “unexpurgated” work, as it were, is available.  For 10 or 15 “large,” it’s a bargain you can’t refuse.

But who left the book in the cab way back when, and how did he feel when he realized what he had done? Did he tell his bosses, or did he suddenly understand that “omerta” was a pretty good idea?