Lured by a double agent working for the United States, ten Russian spies, including a professor at the University of Minnesota, his wife, and a classic "sleeper" spy in New York City, were sent by Moscow to penetrate America's secrets. Two FBI agents were killed, and secret formulas were passed to the Russians in a dangerous ploy that could have spurred Moscow to create the world's most powerful nerve gas.

Cassidy's Run tells this extraordinary true story for the first time, following a trail that leads from Washington to Moscow, with detours to Florida, Minnesota, and Mexico. Based on documents secret until now and scores of interviews in the United States and Russia, the book reveals that:

• more than 4,500 pages of classified documents, including U.S. nerve gas formulas, were passed to the Soviet Union in exchange for hundreds of thousands of dollars
• an "Armageddon code," a telephone call to a number in New York City, was to alert the sleeper spy to an impending nuclear attack -- a warning he would transmit to the Soviets by radio signal from atop a rock in Central Park
• two FBI agents were killed when their plane crashed during surveillance of one of the Soviet spies as he headed for the Canadian border
• secret "drops" for microdots were set up by Moscow from New York to Florida to Washington