"Ann Hagedorn has gifted us with a dazzling, gripping, most timely reflection of the Cold War era — and the ongoing legacy of hateful anti-Semitism driving the quest for sanctuary, education, and peace. This captivating, profoundly researched book is required reading for everyone concerned about history and the future."

– Blanche Wiesen Cook, author of Eleanor Roosevelt (Vols. 1-3), and The Declassified Eisenhower

"An eye-opening account of perhaps the Soviet Union’s most successful sleeper agent."

– Kirkus Reviews

"A historical page-turner of the highest order."

– Ronald Radosh, The Wall Street Journal

"Ann Hagedorn is one of those rare writers I trust to keep me reading in these times when the competition for our attention can be overwhelming. But with the fascinating Sleeper Agent, Ms. Hagedorn has once again captivated me with the focus and depth of her superlative investigative talents, in this instance unraveling the secrets of what J. Edgar Hoover called 'the crime of the [20th] century'—Soviet atomic espionage in wartime America."

– Bob Shacochis, National Book award recipient, author of The Woman Who Lost Her Soul

"Sleeper Agent is both an important work of history and a story that’s hard to put down. Ann Hagedorn might have been a master spy herself, so brilliantly has she assembled myriad specks of information into this extraordinary map of an underground America below the surface of World War II and the Cold War."

– James Tobin, author of The Man He Became: How FDR Defied Polio to Win the Presidency

"Compelling. . . . Hagedorn’s well-researched account employs a host of primary and secondary sources to convincingly connect the dots between Koval, the Soviet spy network, and the creation of the atomic bomb."

– Booklist

"From 1940 to 1948, George Koval hid in plain sight, using his real name while gathering intelligence for the Soviet Union about the American atomic project. Ann Hagedorn tells this incredible story and more: Hagedorn's account of this life is a gripping page-turner, almost unbelievable yet true."

– Stephen M. Norris, Director, Havighurst Center for Russian and Post-Soviet Studies, Miami University

"Enlivened by its brisk pace and lucid scientific details, this is a rewarding introduction to a noteworthy episode in the history of Soviet espionage."

– Publishers Weekly

"Expertly researched, psychologically thrilling. . . . Will thrill readers who are drawn to works by Ben Macintyre and Kate Moore."

– Library Journal

"A good adventure story, well told. . . . How Koval’s involvement was ultimately revealed is compelling, but the even more gripping narrative is how and why he became a spy in the first place. . . A story worthy of John Le Carré."

– The New York Journal of Books