Cillian Murphy’s ‘Oppenheimer’ Grapples With Creating Atomic Bomb in Trailer

“They won’t fear it, until they understand it. And they won’t understand it, until they’ve used it,” Cillian Murphy’s J. Robert Oppenheimer says in the new trailer for the biopic, Oppenheimer. Written and directed by Christopher Nolan, the film arrives July 21.

Based on the Pulitzer Prize-winning biography American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer by Kai Bird and the late Martin J. Sherwin, the biopic traces the life and of the theoretical physicist dubbed the “father of the atomic bomb” for his contributions to the Manhattan Project, the government research operation responsible for creating nuclear weapons. Oppenheimer helmed Los Alamos Laboratory, which designed the bombs.

In between the designing of the bomb and explosive imagery, Murphy’s Oppenheimer contemplates the gravity of its creation. “I don’t know if we can be trusted with such a weapon, but we have no choice,” he says in the clip. Later he adds, ominously: “Is anyone ever going to tell the truth about what’s happening here?”

The all-star cast includes Florence Pugh as Jean Tatlock, Emily Blunt as Kitty Oppenheimer, Robert Downey Jr. as Lewis Strauss, Matt Damon as Leslie Groves Jr., and Gary Oldman as Harry S. Truman, Benny Safdie as Edward Teller, Michael Angarano as Robert Serber and Josh Hartnett as Ernest Lawrence. Rami Malek, Kenneth Branagh, Dane DeHaan, Jack Quaid, and Matthew Modine also feature in the film.