In the morning of March 11, 2004, Susan Lindauer woke to find five F.B.I. agents at her front door. After reading her her rights, the agents took Lindauer from her home in Takoma Park, Md., to the F.B.I. field office in Baltimore, where she was charged with having acted as an unregistered agent of Saddam Hussein's Iraqi government and otherwise having elevated the interests of a foreign country above her allegiance to the United States. ''The only visible sign of stress is that I'm chain-smoking,'' she said when I met with her recently. Forty-one and free on bail, she wore...