The film opens in 1954 with a tense security hearing for the renowned physicist J. Robert Oppenheimer [sam-waterston], focusing on his past associations and political beliefs. Throughout the movie, we see scenes shifting between this present-day investigation and key moments from Oppenheimer’s earlier life, revealing the complex web of personal, political, and scientific conflicts that shaped his career.
The story revisits Oppenheimer’s youthful ambitions in 1924 when he studies physics at Cambridge under the guidance of Patrick Blackett. Eager to attend a lecture by the influential Niels Bohr [kenneth-branagh], Oppenheimer, in a moment of bravado, secretly injects potassium cyanide into an apple on Blackett’s desk to challenge him, but later manages to meet Bohr himself after stopping him from eating the poisoned fruit. Impressed by his sharp intellect and curiosity, Bohr encourages Oppenheimer to pursue further education, believing his potential is best realized through independent study.
Oppenheimer then travels to Göttingen, where he works toward his PhD with notable figures like Isidor Rabi [david-krumholtz] and Werner Heisenberg. His admiration for Heisenberg’s work profoundly influences him. Returning to the United States, Oppenheimer begins teaching at Berkeley, where he earns the affection of students and colleagues alike, including Ernest Lawrence [josh-hartnett], a Nobel laureate. His initial lectures attract only a handful of students but soon grow into a large, vibrant class.
His personal life becomes intertwined with his political views when he attends Communist Party gatherings with his younger brother Frank [dylan-arnold] and makes acquaintances such as Haakon Chevalier. Oppenheimer also carries on a romantic relationship with Jean Tatlock [florence-pugh], with whom he shares intimate moments and intellectually stimulating conversations. After Jean’s death by apparent overdose, Oppenheimer’s troubled mental state surfaces, hinting at underlying guilt and turmoil.
Meanwhile, Oppenheimer’s political leanings and associations draw the attention of government officials. Katherine “Kitty” Puening [emily-blunt], a fellow Communist, becomes his wife, and together they have a son, Peter. The film depicts their tumultuous marriage, marked by Oppenheimer’s infidelity and Kitty’s struggles with alcoholism. Despite personal hardships, Oppenheimer’s reputation as a brilliant scientist leads to his recruitment by General Leslie Groves [matt-damon] to lead the Manhattan Project—a secret endeavor to develop an atomic bomb during World War II.
Oppenheimer assembles a team of top scientists at Los Alamos, including Richard Feynman, Kenneth Bainbridge, Seth Neddermeyer, and others, who work tirelessly on a project shrouded in secrecy. The scene intensifies with the arrival of Edward Teller [david-suchet], who introduces the dangerous potential of the hydrogen bomb, sparking concerns among Oppenheimer and his colleagues about the destructive power they are unleashing upon the world.
The narrative explores the moral and ethical dilemmas faced by the scientists as they realize the destructive capabilities of their work. The team carries out testing at Trinity, culminating in the monumental detonation that produces a massive mushroom cloud. Oppenheimer, witnessing the explosion, famously recalls the quote from the Bhagavad Gita: > "Now I am become Death, the destroyer of worlds." The success of the test marks a turning point but also weighs heavily on his conscience, especially as Hiroshima and Nagasaki are bombed, causing unprecedented devastation and loss of life.
As the Cold War begins, fears of Soviet espionage and nuclear proliferation intensify. Oppenheimer’s past associations, including his relationship with Chevalier and his left-leaning political views, come under scrutiny. The government, worried about communists infiltrating their project, launches a security hearing to question his loyalty. Key figures like Edward Teller and Leslie Groves give damaging testimonies, and Oppenheimer’s connections to Chevalier, Lomanitz, and other leftists are scrutinized.
During the hearings, Oppenheimer’s personal life is also examined. His ongoing affair with Jean Tatlock is brought up, culminating in her tragic death by apparent overdose, with hints that she may have been murdered to suppress her influence. His marriage to Kitty also suffers, as she grows increasingly resentful and struggles with her own demons.
Amid the investigation, Bohr [kenneth-branagh], who is brought back from Europe, warns Oppenheimer of the terrifying power they have given mankind. The film emphasizes the philosophical and moral implications of their work, with visions of global nuclear catastrophe haunting Oppenheimer’s conscience. Despite some court affirming his loyalty, his security clearance is revoked, and his political influence diminishes, marking a symbolic defeat.
In the final scenes, Oppenheimer reflects on the consequences of his scientific achievements during a conversation with Albert Einstein [tom-Conti]. They discuss the potentially world-ending chain reactions initiated by nuclear weapons. Oppenheimer, in a 1963 scene, receives the Enrico Fermi Award from Lyndon B Johnson, contemplating how their work may have doomed humanity to an uncertain future. Visions of nuclear explosions around the world flash before him, symbolizing the ongoing threat of annihilation.
Throughout the film, themes of ambition, guilt, moral responsibility, and the cost of scientific progress are explored deeply. It paints a poignant picture of one man’s journey from brilliant scientist to a haunted figure burdened by the enormous consequences of his contributions to modern warfare.
