Researching spy history is a difficult business. Spies carefully cover their tracks and intelligence agencies classify everything and release their records only after many years, if at all. Given these difficulties how do historians reconstruct espionage history? SPY Historian Mark Stout explores this issue with Dr. R. Bruce Craig, the author of Treasonable Doubt: The Harry Dexter White Spy Case. Hear Craig describe how a receipt for $1.25 allowed him to discover the real identity of the mysterious “Agent Zero” who spied for the Soviets before World War II. Also listen as Craig tells of his forthcoming book about Alger Hiss and how he has brought lawsuits that forced the government to open up sealed grand jury records for Hiss and Julius and Ethel Rosenberg.