“In this town, it can all change… like that,” Rick Dalton said with a crisp snap of the fingers in “Once Upon A Time In Hollywood.” And yep, it’s all just flipped upside down. David Fincher and Brad Pitt are putting aside everything they’re working on to direct and star in a sequel to “Once Upon A Time In Hollywood” written by Quentin Tarantino.

Now Fincher and Pitt working together isn’t a surprise; the “Se7en” filmmaker gives Pitt first dibs on all his projects (he turned down “The Killer” for example), but directing a film based on the screenplay of Tarantino, who always directs his own material, is not only an unexpected shocker, it’s a cinematic first.

What’s more, the project is being set up at Netflix, where Fincher has a first-look deal and aims to shoot quickly this summer.

From what I understand, this is the screenplay that Tarantino’s “The Movie Critic” evolved into when the writer/director couldn’t put the pen down and kept exploring the adventures of Cliff Booth.

Tarantino must have loved the script and didn’t want it to languish in a drawer because sources close to the filmmakers tell us he approached Fincher, and Netflix has quietly put together the deal, which will probably end up being around a $200 million budget to shoot in California this July—yep, it’s being fast-tracked and happening fast, meaning we’ll get additional casting soon.

Fincher loves working with Pitt, and the package of it all was clearly super enticing to everyone.

No other cast is set. Whether Leonardo DiCaprio will return as Rick Dalton is very doubtful. Maybe a cameo wouldn’t be out of order, but it doesn’t appear like it’ll happen: this sounds very much like a Cliff Booth film, though most plot details are unknown (Update: The Insneider says he’s in it, we’ll see?). Oh, and Margot Robbie and her people got wind of it and said she’s available if they need her.

The film’s official title is unknown, and insiders tell us that Netflix may have paid over $20 million for Tarantino’s screenplay.

Fincher, as per usual, has many fires in the iron but is putting them all aside for this unprecedented film. He is still developing his “Squid Game” spin-off series with Dennis Kelly (“Utopia”), which will feature a different title and may not even be closely related to the South Korean series.

The Western project Fincher was rumored to be making “Bitterroot” is real too, but it’s also taking a backseat. And who knows if that “Chinatown” series remake with Tom Pelphrey and written by Robert Towne before he passed away last year will ever get made.

Incidentally, Fincher has also been working with “Gone Girl” screenwriter Gillian Flynn on another project, but it’s unclear what that one is.

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As for Tarantino, what he’s up to next for his tenth and final film is unknown, but clearly, he wasn’t quite finished with Cliff Booth and this “Once Upon A Time In Hollywood” sequel/spin-off, and he wanted someone to make it.

Netflix is buying InterPositive to accelerate the use of artificial intelligence in its filmmaking. The startup has developed a suite of tools that allow filmmakers to alter existing footage. David Fincher has already used the products on an upcoming film starring Brad Pitt.