In 1946, genius linguist and codebreaker Meredith Gardner discovered that the KGB was running an extensive network of strategically placed spies inside the United States. Over the course of the next decade, he and young FBI supervisor Bob Lamphere worked together on Venona, a top-secret mission to uncover the Soviet agents and protect the Holy Grail of Cold War espionage—the atomic bomb. As the author of Dark Invasion: 1915 relates in this spellbinding history, Lamphere and Gardner relentlessly followed a trail of clues that led them to Julius and Ethel Rosenberg, unaware that they were up against a KGB master spy who intended to stay one step ahead of them.