Can you summarize chapter 9

Chapter 9: In 1939, Allan arrived via ship in New York. Lacking official papers, Allan was kept in a holding cell for a few years. He was eventually flown to Los Alamos, New Mexico, because of his valuable knowledge in explosives. He served coffee to the prestigious scientists who were working on the first atomic bomb, including Alan Oppenheimer. During one such meal, Allan interrupted the gathered brains to supply the critical idea necessary to complete the bomb. Vice President Harry Truman, who happened to be visiting to check on the progress, was impressed by Allan's genius insight and invited Allan to a private dinner. The dinner sadly concluded with news served to Truman that President Roosevelt had just died.