'Interstellar' Stars on Keeping Secrets of Christopher Nolan's Space Epic

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John Lithgow

"I set my script down once at Ralphs grocery store in L.A., and I walked away from it for maybe all of three minutes … I've never been so scared in my life"

The many secrets of Christopher Nolan's carefully guarded epic sci-fi film Interstellar will begin leaking out this week as the film rolls out in theaters. But Nolan and the film's cast and crew have taken great pains to keep the film's many twists, turns and surprises under wraps.

Still, one of the film's most prominent voices almost spoiled everything.

Watch more The Hollywood Reporter's Full 'Interstellar' Discussion With Christopher Nolan, Stars

Bill Irwin, who lends his voice to a robot that has a significant role in the film, was on set and involved with filming, per Nolan's request, even though the director knew it would be cheaper to hire someone to do the voice work at the end of the project. So, Irwin carried his script around with him, even to the grocery store — where disaster almost struck.

"I set my script down once at Ralphs grocery store in L.A., and I walked away from it for maybe all of three minutes. I've never been so scared in my life," Irwin told The Hollywood Reporter at Tuesday night's New York City premiere, adding that he ran back and was able to grab his script before anyone snatched it.

The film follows Matthew McConaughey and Anne Hathaway's characters as they venture into space in search of a way to save the human race, but beyond that there's much that remains unknown about what happens and who participates in the movie.

Read more 'Interstellar's' Christopher Nolan, Stars Gather to Reveal Secrets of the Year's Most Mysterious Film

Two of the film's veteran stars said it wasn't at all challenging to keep the plot under wraps — they relished keeping the secret.

"Every time someone would ask me, I would say I'm sworn to secrecy, I can't tell you anything," Ellen Burstyn told THR.

John Lithgow, who plays McConaughey's character's father-in-law, added: "I'm an actor. We like to surprise people. We all have secrets, we actors … It makes you feel very privileged to know the story of a Christopher Nolan film … I like the culture of secrecy because it goes to the heart of storytelling."

He also relished telling co-star David Oyelowo, who has a very minor role in the film, what the movie was about, since the actor hadn't been told any details, Lithgow said.

See more Christopher Nolan's Filmography: 'Interstellar,' 'Dark Knight' and 7 Others

"They had not told him the story of the movie he was in," Lithgow explained. "We went out to supper and he told me he didn't know, so for 20 minutes I told him the plot of the film, and his jaw dropped open. His eyes were like saucers, and he said, 'My God, I am in such a great movie.' "

But two of Interstellar's younger stars struggled with having to keep details of the movie they were working on from their friends and family.

"I always wanted to talk about it with friends but they made me sign a nondisclosure agreement and [everything was] very hush-hush," Timothee Chalamet, who plays McConaughey's character's young son, Tom, said. "I read the script on the set. We couldn't take it home or anything. That adds to the fun of it all. The mystery."

See more Matthew McConaughey's Diverse Film Resume, From 'Dazed and Confused' to 'Interstellar'

Mackenzie Foy, who plays Tom's sister, Murph, added: "My mom knew because she read the script, or at least my parts of the script, but I couldn't tell my brother or my dad. They got to see it at the premiere, and I was like, 'OK, now we can discuss.' "

Interstellar, which co-stars Anne Hathaway, Jessica Chastain, Casey Affleck and Nolan's good-luck charm Michael Caine, hits select theaters on Wednesday.