While buzz was near-radioactive at the U.K. premiere of Nolan’s twelfth feature film on Thursday evening, the possibility of SAG-AFTRA’s actors strike loomed over the red carpet at the Odeon Luxe cinema. The event was moved up an hour only the night before in case a strike action commenced and forced the cast to stay home.

But the ever-enigmatic Cillian Murphy led the way, admitting he relished the opportunity to impress as Nolan’s frontman after years of collaboration between the pair.  “It’s a dream,” he said. “He’s one of the best directors living.”

“I’m just gonna say it: This is my best film,” he proudly announced. “This is what a summer blockbuster was when I was growing up… It kind of changed your life. It’s why Christopher Nolan is who he is.”

Nolan’s project follows the life of J. Robert Oppenheimer and the sinister inner workings of the Manhattan Project, as a team of scientists work through World War II to create a weapon capable of wiping out the planet.

And climbing into the brain of the father of the atomic bomb cannot have been an easy task. Luckily, there was not a surprising synergy between the character and himself, he reveals. “We don’t really have that much in common,” said Murphy of playing the titular role. “But I don’t think you need to have commonality with the protagonists to play them.”

He stars alongside Emily Blunt, playing the theoretical physicist’s wife, Kitty. Blunt joined the praise for Murphy’s performance: “He’s just wonderful, he’s happy. And we trust each other,” she said. “You have an accelerated friendship when you work with people, it’s like a secret language.” (The two headlined A Quiet Place 2.)

“We all stayed in the same hotel, but me and Matt and Josh were all in these cabins next to each other. And it was terrifying; when I arrived it was pitch black, there was no light. I said, ‘If any of you hear me screaming in the night, you’re gonna come running, all of you, save me from whatever is happening.’ We called it the cellblock.”

Hartnett, playing American physicist Ernest Lawrence, did not get into just how big of a responsibility protecting a star like Emily Blunt is. He did say a Nolan set feels like a “family,” and warned audiences of what a film like Oppenheimer could do.

Nolan himself, along with Pugh, Damon, and Downey Jr., were selective with the press. Reporters were warned away from mentioning the impending SAG-AFTRA strike. Early-access viewers have already voiced their shock at the film’s ending, when theory becomes reality for a weapon like Oppenheimer’s.

“I think it’s a masterpiece,” says friend and colleague of Nolan’s, Kenneth Branagh, who plays Danish physicist Niels Bohr. “The scale of the ambition, the size of the story, the characters involve. It’s an immensely tall order. The state of his filmmaking, that he’s able to do that and still have the cinematic panache. It is really thrilling.”