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 Lampshere 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.Opposites in nearly every way, Lampshere and Gardner relentlessly followed a trail of clues that helped them identify and take down the Soviet agents one by one, including Julius and Ethel Rosenberg.They uncovered atom spy Klaus Fuchs in the UK. But at the centre of this spy ring, seemingly beyond the American agents’ grasp, was the mysterious master spy who pulled the strings of the KGB’s extensive campaign. Lampshere and Gardner began to suspect that a mole buried deep in the American intelligence community was feeding Moscow Centre information on Venona.They raced to unmask the traitor and prevent