While investigating makeshift runways, the team finds reason to believe Adolf Hitler would have had a stopping point on the way to Spain; Lenny and historian James Holland head to Denmark, where they investigate an airstrip and a bunker system.

A document shows Adolf Hitler and Leon Degrelle may have moved from Denmark to San Sebastian, Spain; the South American team speaks to an eyewitness who claims his father worked for Hitler's right-hand man, Martin Bormann, after the end of the war.

While following leads on a Nazi escape network, the teams in Southern Spain and Northern Argentina both make discoveries of vast tunnel systems in the mountains.

Bob and John’s investigation continues in Spain, Morocco and Argentina. The teams look into Hitler’s possible escape route while uncovering a plan for a Nazi 4th Reich.

Digging deeper into reports about the Fourth Reich, Bob and John send the team to a rumored weapons testing site in Germany, and a mysterious deserted island in Argentina that could have housed nuclear facilities with Nazi ties after the war.

With Peron toppled from power, Hitler and Bormann could have been forced to flee Argentina. Following leads from declassified files, Bob and John send their teams into Chile and Paraguay to investigate Hitler’s whereabouts if he were forced to escape.

Bob and John have followed hundreds of international declassified files all the way from Berlin to Chile, where they now investigate a secretive German community with reported Nazi ties. Inside the compound they find clues pointing to the potential forming of a Fourth Reich.