The next step in the operation is to choose potential targets to attack. The governmental committee narrows their targets to five potential locations: Kyoto, Hiroshima, Yokohama, Kokura, and Niigata. Kyoto is ruled out immediately, as it is a favorite tourist destination for Stimson, the war secretary.

Lieutenant Jacob Beser, who had enlisted after the Pearl Harbor attacks and who eventually became a radar expert, arrives late for the committee meeting. Beser works with the group who developed the proximity fuse for the weapon, allowing it to be detonated before impact at a specific height in order to spread the blast radius. He also acts as a general troubleshooter, assisting the committee in making their first choice for an atomic strike: Hiroshima.

In a Japanese town called Kimita, a little girl named Hideko Tamura spends the day learning and working in the local temple. Her parents sent her there from their home in Hiroshima—along with many other children from the area—for safekeeping in case the city of Hiroshima is bombed, as they know it is a likely target. Hiroshima has prepared itself well for war, digging wells and setting up bomb shelters everywhere.