This illustrated 3,500 word monograph represents all the known facts about Julius and Ethel Roosenberg, the couple accused of stealing America's atomic bom secrets and handing them over to the Soviet Union. But the Rosenbergs were not the most important atomic spies to be discovered. Who led the FBI and other law enfocrement to the Rosenberghs? His name was Klaus Fuchs, and he was, the most important atomic spy in history. Not any of the notorious collaborators in the saga of the theft of the atom bomb secrets had been as important to the Russian effort as Fuchs.