This week on History Happy Hour: The little-known story of FBI agents who went undercover to hunt down U.S. traitors on foreign soil during World War II. The goal: to identify and capture U.S. citizens plotting against their own country in the shadows of war-torn Europe. To accomplish this, a small group of federal agents assumed new identities to infiltrate underground networks, interrogate key suspects, and conduct a secret manhunt as harrowing as any Hollywood cliff-hanger.

In this encore episode we talk to Stephen Harding, author of G.I. G-Men: The Untold Story of the FBI's Search for American Traitors, Collaborators, and Spies in World War II Europe. HHH Alum Andrew Roberts says “Stephen Harding, America’s leading commentator on the extraordinary scenes that define the finale of World War II, has done it again.” And you’ll also get to see what happens when Rick’s hotel has a fire alarm! (Goodbye Rick!)

Stephen Harding is the author of ten previous books, including the New York Times bestseller The Last Battle and Last to Die. He is a longtime journalist specializing in military affairs. For nearly two decades he was on the staff of Soldiers, the official magazine of the US Army, reporting from Northern Ireland, Israel, Egypt, New Zealand, Bosnia, Kuwait, and Iraq. Currently he is editor-in-chief of Military History magazine.