During World War II, as Nazi forces besieged the Russian city of Leningrad, scientists at the city’s famed seed bank made a pact to protect the collection and consume nothing, even if it could have extended their lives. The siege lasted nearly three years, killing an estimated 1.5 million people. A new book by British author Simon Parkin details this foundational story of modern plant gene banking, and what it means when hunger is used as a weapon of war.