The venerable book business is experiencing a moment of turmoil, as evidenced by two events last week.

A glitzy party on Wednesday triggered the most extravagant book launch of the year (if not the decade). It is being funded by a neophyte publisher celebrating a book that readers probably will never find in their bookstores. It’s not another “Fifty Shades of Gray” sequel but a memoir by Penny Marshall, published by Amazon. No, not Simon & Schuster, but Amazon.

Meanwhile, Barry Diller and Scott Rudin, two other newcomers to the book business, last week unveiled a new venture called Brightline that will publish e-books (and ultimately hardcover tomes), defying the downbeat aura surrounding the industry. Working in partnership with an online company called Atavist, Diller emphasized that he will allocate substantial funding for “marketing and promotion” — two words unfamiliar to the old-line publishing houses.

Relishing the world of risk taking, I decided to attend the book party for Penny Marshall at Manhattan’s Monkey Bar, thereby encountering such celebrity celebrants as Penny herself, David Geffen, Lorne Michaels, Regis Philbin and the ubiquitous Diller. The tab for the lavish event was picked up by Amazon, which paid a reported $1 million for rights to the book plus well north of $500,000 to promote it.

Because Amazon already controls roughly 65% of e-book sales, retailers like Barnes & Noble are welcoming the company to the hardcover business by refusing to stock Penny’s book in their stores.

None of this seemed to daunt the feisty filmmaker, whose candid, occasionally gritty memoir relates details of her romances (Rob Reiner and Art Garfunkel), her bouts with cancer, her abortion (she insisted on being accompanied by her shrink) and her quarrels with various co-stars and studio executives.

Coincidentally, Penny’s brother, Garry, who helped launch her career, has also come out with a recent memoir, titled “Happy Days” (Penny’s title is “My Mother Was Nuts”). As the titles would indicate, Garry’s account of events is considerably sunnier than Penny’s.

“He’s a writer,” she explains. “He can make things up.”

To illustrate, she notes that in Garry’s version, Mommy wasn’t even nuts.

Several major movies are undergoing reshoots to fix plot points, but the recrafting of “Red Dawn” is unique (and bizarre) on several counts.

In the original 1984 “Red Dawn” the heavies were Russians. In the remake, to be released in November, the bad guys started out as Chinese, then were reshot and re-edited as North Koreans (which will surely help Chinese box office results). Between “Red Dawn” the original and “Red Dawn” the redo, the principal characters have evolved from victims to heroes. What started life as an antiwar movie will now reappear as a swaggering action film.

And John Milius, who directed the first film, is on record as stating that the idea of a remake is “stupid.”

“Red Dawn” was originally written by Kevin Reynolds as a rethinking of “Lord of the Flies.” Reynolds wanted to direct the film but was tossed by the studio, which favored Milius’ more action-oriented approach. Production of the film was supervised by Gen. Alexander Haig, then a member of the MGM board of directors.

Through all this the premise remained the same — almost: A foreign power invades the U.S., and is met by a ragtag guerrilla band of American kids. In the original the defenders included a heroic young actor named Charlie Sheen. Chris Hemsworth heads the cast of the new film. And Milius’ position as director was assumed by veteran stunt coordinator Dan Bradley.

Perhaps appropriately, the new “Red Dawn” will have its premiere at the Alamo Drafthouse, where the Fantastic Fest screens its festival films.

I hope the drinks are on the house.