“Physics is hard,” says author Sara Paretsky, creator of the V.I. Warshawski suspense series, via press materials. “But it’s also intensely interesting, even exciting. It lies at the heart of the 20th century’s technological leaps and its horrifying wars, and makes for a very engaging backstory for a book.” Paretsky’s latest installment in the series, Critical Mass is the story of Kitty, a woman whose mother, a noted scientist, perished in the death camps of WWII. Inspired in part by the real-life story of Marietta Blau, a gifted physicist who managed to escape a similar fate with the help of Albert Einstein but never reached her full potential as a result of lost time and resources, Critical Mass gives Warshawski a new wrestling partner: science. In sorting out the current dangers Kitty faces, Warshawski discovers a mass of lies and secrets that lead her back to the 1940s, when America, England, Japan and Germany were in a race to develop the first atomic bomb.