Cathal begins with an investigation into the notorious Andrija Artukovic, Nazi Minister of the Interior in Croatia and the man responsible for the deaths of over 1,000,000 men, women and children in concentration camps. His time here is shrouded in mystery, as the Department of Foreign Affairs still refuses to release the file on this man. Programme One also focuses on Celestine Laine, leader of the Bezen Perrot, a Waffen SS unit responsible for the torture and murder of civilians in occupied Brittany, and Pieter Menten, responsible for the deaths of hundreds of Jews in Poland. Why was the Irish state prepared to harbour men such as Artukovic and Laine, while Jewish refugees were refused asylum? To find out the answer, Cathal talks to historians and other experts, uncovers government documents, and investigates the thorny issue of anti-Semitism in mid-20th century Ireland.

In Programme Two, Cathal O'Shannon investigates how the cold war opened new channels for Nazis seeking sanctuary here. He tells the story of 'the most dangerous man in Europe' and Hitler's favourite soldier - Otto "Scarface" Skorzeny, a James Bond figure who famously rescued Mussolini from a mountaintop fortress. Skorzeny was feted by the Dublin social glitterati, even hobnobbing with a future Taoiseach. He also looks at Helmut Clissmann, the man tasked by the Nazis to recruit the IRA for their war against Britain. Cathal moves on to investigate the Flemish nationalists who became Nazi collaborators - men like Albert Folens, who went on to become a successful publisher of Irish schoolbooks, Albert Luykx, who fled justice in Belgium and later conspired with Charles Haughey and Neil Blaney to import arms for the IRA, and Staf Van Velthoven, the last surviving of 'Ireland's Nazis'. The style is intriguing and investigative, utilising archive, interviews and drama reconstruction. On a journey that crosses three continents, Cathal O'Shannon discovers who these men were and asks why they were allowed to build lives in postwar Ireland. Steeped in political and religious intrigue, this groundbreaking documentary series reveals the truth about one of the most sensitive and unexplored areas of Ireland's past.