Born in Czechoslovakia, Lilli Hornig and her family immigrated to the United States from Berlin after her father was threatened with imprisonment in a concentration camp. She was a young chemist when her husband, Don Hornig, was personally asked by George Kistiakowsky to come to Los Alamos to work on a secret project. At first she worked on plutonium chemistry, but after concern was raised that plutonium could cause “reproductive damage” for women, she began working for the explosives group. A witness to the Trinity test, she recalls the vivid colors of the blast. Lilli signed the Los Alamos scientists’ petition to have a demonstration of the bomb’s destruction rather than dropping it on Japan.