Fat Man and Little Boy

In September 1942, U.S. Army Corps of Engineers Colonel Leslie Groves is assigned to head the ultra-secret Manhattan Project, aiming to beat the German nuclear program. He brings military organization and discipline to a top-secret effort, previously focused on other national projects like the Pentagon. The assignment sets the stage for a massive, cross-country scientific undertaking.

Groves selects J. Robert Oppenheimer, a Berkeley physicist, to head the project team. Oppenheimer's charisma and intellect make him a natural leader for a diverse group of scientists. The recruitment marks a pivotal shift from military oversight to scientific leadership.

Oppenheimer chooses a remote mesa near Los Alamos Canyon to house the new research facility, keeping the team insulated from external pressures. The secluded site is intended to protect sensitive work and foster focused collaboration. This setting would become the cradle of the Manhattan Project’s most famous work.

As the project advances, military demands and scientific ideals clash. Groves pushes for rapid progress, while Oppenheimer and the team wrestle with whether personal ethics should influence their work. The result is ongoing friction as components move toward a critical, time-sensitive completion.

During a high-risk experiment nicknamed Tickling the Dragon's Tail, a reactor component is dropped and recovered by hand to prevent a disaster. The handler is exposed to a lethal dose of radiation and dies days later after a painful battle with swelling and deformation. Kathleen Robinson, a nurse, witnesses the tragedy in the base hospital.

As the project expands, investigators scrutinize potential espionage and communist sympathizers within the broader scientific community. The scrutiny creates anxiety and distrust among staff, threatening the unity needed for a project of this scale. The atmosphere grows tenser as leaks or suspected leaks become a daily concern.

Groves orders Oppenheimer to sever his relationship with Jean Tatlock after spying concerns surface about her. Oppenheimer breaks off the affair, unable to fully explain the reasons to her, and the personal tension bleeds into his professional life. The rift compounds the emotional strain surrounding the project’s secrecy.

Tatlock, unable to cope with the heartbreak and isolation caused by the project’s secrecy, is later found dead, apparently by suicide. The tragedy haunts Oppenheimer and underscores the collateral human costs of the project. The incident feeds the moral questions the scientists grapple with throughout development.

To mitigate the risk of a single point of failure, the project pursues two different bomb concepts: Fat Man, a plutonium implosion design, and Little Boy, a uranium gun-type design. The scientists and engineers work on simultaneous development across multiple sites to diversify the project’s prospects. The dual paths exemplify the tension between competing scientific approaches.

Across facilities, the two designs advance toward practical prototypes. The plutonium implosion method for Fat Man and the uranium gun-type method for Little Boy represent radically different engineering challenges. The project races toward a dramatic test and eventual deployment.

The Trinity test, conducted at the Trinity Site in the Alamogordo Desert, detonates the first nuclear device in history. At 05:29:45 on July 16, 1945, a massive mushroom cloud rises as companions miles away feel the blast and the winds roar across the desert. The test confirms the weapon’s viability and accelerates the coming atomic age.

Following the Trinity test, the Fat Man and Little Boy weapons are deemed successful, bringing the Atomic Age into reality. The successful demonstration and production enable deployment during World War II and reshape global power dynamics. The project ends its long arc, having achieved its strategic aims but at great human and moral cost.