Rian Johnson Reveals the MVP of His All-Star 'Knives Out' Cast (Exclusive)

Plus, a check-in about the 'Last Jedi' director's 'Star Wars' trilogy.

Rian Johnson returns to his roots with Knives Out, a whodunit that is more in line with his earlier crime dramas, like Brick and Looper, than anything from a galaxy far, far away. It's an idea the writer-director began percolating on a decade ago, though his intrigue in the genre dates back even further.

"It all came from me being a big Agatha Christie fan ever since I was a little kid," Johnson tells ET's Ash Crossan. "I love a good whodunit. It's just the most fun type of book, the most fun type of movie. You have, like, a weird, eccentric detective; you have a big, fun cast of suspects. It's kind of self-aware and fun, but it's still a good mystery."

The mystery here revolves around the murder of famed crime novelist Harlan Thrombey (Christopher Plummer) and the subsequent investigation into whether any member of his family had a hand in it, a case led by celebrity detective Benoit Blanc (Daniel Craig).

To make up the dysfunctional Thrombey family, Johnson enlisted Toni Collette, Jamie Lee Curtis, Chris Evans, Don Johnson, Katherine Langford, Jaeden Martell and Michael Shannon, with Ana de Armas as Harlan's nurse and LaKeith Stanfield as a local police detective. "When you have a cast with that many amazing people, you want to make sure everybody has enough to do in it," he explains. "That is the hardest thing: making sure everyone gets their moment."

Yet, Johnson's favorite scenes to shoot were of the entire cast together in the same room, throwing accusations at one another or fighting over a will reading. "What's fun about it is not just Captain America telling everyone to eat poo-poo, what's fun is all those actors in the same room," he says in reference to a scene teased in the trailer, in which Evans directs his relatives to "eat sh*t." "I just got to sit back and have a huge smile on my face at the monitor." While the entire cast was stellar, Johnson saves special praise for the incomparable Curtis.

"First of all, she would be early [every morning]. She'd beat all of us to set," he recalls. "Sometimes she would show up on set when she wasn't even supposed to be in the scene and just be hanging out, and I would get really confused and kind of nervous. So I would put her in the scene! I was like, 'Jamie Lee Curtis is here! Film her!' She got into scenes she wasn't even supposed to be in -- just because she was there!"

The mysteries of Knives Out won't be fully revealed until it opens n theaters on Nov. 27, but the film earned rave reviews out of its premiere at the Toronto International Film Festival. More than anything, Johnson is able to breathe a sigh of relief that no one has poked holes in his intricately designed plot.

"You do all the work and you get it as airtight as you possibly can, [but] every time an actor would come up to me on set and I could see in their eyes they had a question, my heart would stop," he says. "I was like, 'Michael Shannon is going to ask me the thing that I'm going to not have an answer for and the whole thing is going to unravel.'"

Following Knives Out, Johnson has at least one project in the pipeline: In November 2017, Lucasfilm revealed that Johnson, who helmed The Last Jedi, will create a new trilogy of Star Wars films. Any update two years on? "No, I got no update," he coyly says.

Which doesn't mean the trilogy has fallen to the wayside. Recently, Star Wars fans speculated whether Johnson was casting doubt on his series actually happening after he said during a red carpet interview that he would be "thrilled if it happens."

"Did I say 'if'? Oh god," he says with a laugh while speaking with ET. "I have no update at all. But I'm still working with Lucasfilm on it, and they're figuring out when they do what and everything."