After a CIA officer and an FBI agent shake hands, the saying goes, each man quickly counts his fingers. For more than fifty years, the rivalry between spies and G-men has informed and defined most major blunders in American counterintelligence, from Pearl Harbor to the Kennedy assassination to the World Trade Center bombing. Relying on newly declassified documents and in-depth interviews with former agents, Mark Riebling has written the first extended account of this secret and costly schism.

Riebling reveals how the World War II feud between FBI Director J. Edgar Hoover and William J. "Wild Bill" Donovan, the godfather of CIA, drove a wedge between foreign and domestic spycatching, creating a fundamentally flawed intelligence system.

He shows how the problems arising from this arbitrary split shaped McCarthyist loyalty probes, the U-2 affair, and plots to kill Fidel Castro; sparked major political scandals, from Watergate to Iran-contra to Iraq-Gate; hobbled the 1960s hunt for spies in CIA; perhaps contributed to Jack Ruby's murder of Lee Harvey Oswald; and allowed Russian mole Aldrich Ames to serve almost a decade in CIA before being caught.

Riebling also adds to the public record new clues to the likely identity of Deep Throat, and the names of two U.S. spy chiefs investigated as possible Soviet agents.

Among the many singular characters Riebling introduces us to are Dusan M. Popov, a double agent who shared World War II adventures with the British intelligence officer Ian Fleming and was the real-life model for James Bond; renegade FBI agent William King Harvey, who became chief of anti-Soviet operations for CIA and, it is said, drank three martinis at lunch and Jack Daniel's the rest of the time; CIA Director Richard Helms, "the man who kept the secrets," whose refusal to share information with Hoover precipitated a total break in CIA-FBI relations; Sam Papich, the Montana-bred ex-pro football player who served for two decades as FBI liaison officer to the Agency, until Hoover suspected him of collaboration with the enemy (CIA, not KGB); and, of course, the now-legendary James Jesus Angleton, who for the twenty iciest years of the Cold War was CIA's chain-smoking, fly-fishing, orchid-growing, poetry-loving chief counterspy.