LOS ANGELES — J. D. Salinger was good at keeping secrets.

Harvey Weinstein, well, not so much.

But now the film producer may have to adopt the air of mystery for which Salinger was so famous. His company is preparing to offer a peek at a documentary about Salinger that is one of the unlikeliest projects ever to join its menagerie of potential Oscar contenders and box-office bait.

The film, “Salinger,” has been nine years in the making and is scheduled for release on Sept. 6. It is written, produced and directed by Shane Salerno, who is mostly known as a writer of action features like “Savages,” “Alien vs. Predator: Requiem” and “Armageddon.”

Selling the film may test even Mr. Weinstein’s Barnum-like skills. Moviegoers will be kept intentionally in the dark about what new information Mr. Salerno might have about the reclusive writer’s life — Mr. Salinger’s son, Matthew, challenges the notion that anyone close to his father in recent decades cooperated — and the Weinstein Company will have to strike a delicate balance in its marketing. It will have to raise the curtains a little, but not too much, as it seeks to build anticipation for the release.

As Mr. Salerno delivers his final cut, the marketers face particularly tough decisions about how much to show in a trailer. They must also figure out whether a screening at a late summer film festival, where prize contenders often start their march toward the Oscars, can work for a picture that has to protect its secrets while selling them.