When she was safely alone, she used a letter opener to slit open the envelope from General Leslie Groves, The War Department, Office of the Chief of Engineers, Washington, D.C. Inside was a single, typewritten sheet of paper signed by Groves himself.

May 1, 1943

Dear Dr. Lindstrom:

As we discussed previously, you have agreed to employment at my discretion.

Please present yourself at Pennsylvania Station in New York City on May 7, 1943, at one o’clock in the afternoon. You will be met at the station, provided with a ticket, and escorted to the train by my representative. A hired private car will meet you at your designated stop and transport you the rest of the way to your final destination.

This assignment carries with it the burden of absolute secrecy. You must tell no one of these instructions, nor convey any information whatsoever to anyone, including your parents and family members, for the duration. Your country is counting on you.

Sincerely,

General Leslie R. Groves

Nora read the letter twice. May seventh? That was less than a week away. Graduation was scheduled for May sixteenth. How would she explain to her parents that she was going to miss graduation? Not only that, but she couldn’t tell them anything, including where or when she was going, how she was getting there, how long she’d be gone, or what she would be doing.

What am I going to be doing? Although she knew the rough outlines from her meeting at Pupin Hall, she didn’t know her job title, what the work environment would be, her salary, hours, or living situation. In fact, she knew absolutely nothing, not a single thing more than what Dr. Lawrence, Dr. Oppenheimer, and General Groves had told her, which amounted to pretty much nothing.

For the briefest of moments, all she could hear was her parents’ derision and Anna’s incredulity. Doubt crept in, followed by its close cousin, insecurity. Nora set the letter aside. “You know exactly what you’re doing. You’re using your education to help win the war. The details aren’t important. What matters is that you’re going to make a difference—and not by sitting around knitting scarves, either.”

Nora clenched and unclenched her fists. The strength of conviction surged through her. Not only could she do this, she absolutely would do this. And when it was all over, her parents would be proud and Anna would be in awe of her and what she had accomplished.

She threw open the closet doors, pulled down her suitcase, and hoisted it onto the bed. Tonight she would begin to pack. Tomorrow she would tell her parents she was going away, and she’d be in touch when she could.

Mary wiped her sweaty palms on her pretty red-and-white-checkered gingham dress as Mrs. Platt passed by her with the stack of graded exams for the second time.

“Nice job, Penelope. You showed an excellent grasp of the subject.”