Fat Man and Little Boy (released in the United Kingdom as Shadow Makers) is a 1989 American epic historical war drama film directed by Roland Joffé, who co-wrote the script with Bruce Robinson.

The story follows the Manhattan Project, the secret Allied endeavor to develop the first nuclear weapons during World War II.

In September 1942, U.S. Army Corps of Engineers Colonel Leslie Groves, who oversaw the construction of the Pentagon, is assigned to head the ultra-secret Manhattan Project, to beat the Germans, who have a similar nuclear weapons program.

For the new research facility, he selects a remote location on top of a mesa adjacent to a valley called Los Alamos Canyon, northwest of Santa Fe.

In the base hospital, nurse Kathleen can only watch as he develops massive swelling and deformation before dying a miserable death days later.

While the technical problems are being solved, investigations are undertaken to thwart foreign espionage, especially from communist sympathizers who might be associated with socialist organizations.

The bomb development culminates in a detonation in south-central New Mexico at the Trinity Site in the Alamogordo Desert (05:29:45 on July 16, 1945), where everyone watched in awe at the spectacle of the first mushroom cloud with roaring winds, even miles away.

The character of Michael Merriman (John Cusack) is a fictional composite of several people and is put into the film to provide a moral compass as the "common man".

Even before Oppenheimer was chosen to be the lead scientist of the Manhattan Project, he was under surveillance by the Federal Bureau of Investigation (FBI) due to suspected Communist views.