Content Warning: This section includes graphic descriptions of wounded and dead persons after a nuclear attack, as well as references to suicidal ideation.

Harry Gold hurries to tear up and throw away papers that implicate him in spying. Two FBI agents appear at his Philadelphia home. They’ve been questioning him all week and want to inspect his house. Still insisting that he’s just an ordinary chemist who never goes anywhere, he lets them in. They poke through his books and papers. One agent finds, hidden inside a chemistry book, a map of New Mexico with an “X” that marks a spot where a bridge crosses a river in Santa Fe. Harry could explain it away as curiosity about the Old West, but he realizes that his friends and relatives might risk themselves defending him and then find out he’s duped them all. He decides to confess that he’s a spy.

Early in 1934, young Robert Oppenheimer sits in his car with a date, grad student Melba Phillips, gazing out across San Francisco Bay from their perch in Berkeley. Oppenheimer asks if he might step out for a brief walk; she agrees. He walks away and she falls asleep; hours later, she wakes and finds Oppenheimer is still gone.