LOS ANGELES — Willem Dafoe has said that, for him, the process of making a movie always eclipses the finished product.

But after more than 130 film credits, the 67-year-old actor has finally found a project whose final form is on par with the experience of creating it.

“When I watch this movie, I say, ‘Okay, I feel like I’m there again,'” he said. “Although there’s lots of stuff that we had invented that gets cut out, it feels like the making of it.”

That assertion is impressive, given how much “Inside,” Vasilis Katsoupis’ fiction directorial debut, asked of its lead and virtually only actor.

“It really required a lot of different states and different approaches, I would say. But it was great fun,” Dafoe recalled.

Set entirely inside a single apartment and with no foils for Dafoe’s character to rely on, “Inside” is completely dependent on his performance, which is so compelling you forget he is the only person on screen for the better part of 100 minutes.

It follows an art thief named Nemo (Dafoe) who gets trapped inside a collector’s apartment during a botched heist. Nemo is pushed to his limits, braving extreme temperatures, flooding and limited access to food and water, all within the confines of a luxury Manhattan apartment.

Despite the physical and psychological toll that Nemo suffers throughout the film, Dafoe said he was able to distance himself from his character’s tribulations.

“You’re going to some maybe dramatic places or some difficult places, but you’re also enjoying the interplay with the other people,” he said. “You’ve got the camera, you’ve got the film language behind you, so you’re playing with these things.”

More than just a psychological thriller, “Inside” considers the ways in which art rescues humans in modern society from an isolated existence — a way out from being trapped inside of ourselves. Through his meditations on William Blake’s “The Marriage of Heaven and Hell,” Nemo discerns that liberation can only be attained through creation.

For Dafoe, the philosophical exploration of the human relationship to art was not as apparent in the script, but “really came out in the doing of it,” the actor recalled, reflecting on the ways he found beauty in making art pieces for the film.

“That was so enjoyable. You lose yourself in those things. You don’t necessarily know what they’re for, but they feel so useful and so healthy and so necessary,” he said.

Despite his prolific career, Dafoe said “Inside” allowed the Oscar-nominated actor to flaunt chops he rarely gets to display.

“There are certain things that are purely physical, and you don’t always get to do these scenes with no dialogue,” he said. “Meditative sections that you’re really by yourself and there’s nothing to accomplish.”

And while the specifics of the plot of “Inside,” which wrapped filming in June 2021, may not ostensibly feel universal, almost everyone on this side of the coronavirus pandemic will relate to the film’s scant human interactions, vague conception of time and claustrophobic cinematography.

“Inside” hits theaters March 17.