The Diamond Eye by Kate Quinn

 This page-turner story is based on a real woman, Mila Pavlichenko, who was a top-notch Soviet sniper during World War II--and who later became friends with Eleanor Roosevelt. Mila, a single mother, was a student, slogging along on her dissertation and working in a library, when the Nazis invaded. She had taken shooting classes earlier, so she enlisted, eventually becoming a legendary sniper.

It was a fascinating story, made even more so by current events involving Russia, Ukraine, and that part of the world. There are photos of the real Mila at the end of the book, along with an explanation from the author about which parts of the story she could verify and which parts were fictionalized (ie, a plot to kill FDR). Couldn't put it down.