The era: the 1970s. The location: an airplane en route to Washington, DC. Kathryn Clark Childers chats with a fellow passenger. "Are you visiting?" her seatmate asked. "No, I work there," Childers said, pointing out the window to the White House, which had just come into view. "I'm a Secret Service agent." "Really? I didn't know they let girls pull that duty. I'm not really sure what you do." "It's...