The author interviewed and researched primary sources to reveal the plans Hitler had for invading and occupying England. Some documents and information were released publicly for the first time in this 1961 book. There were intricate plans to kidnap the Royal family, occupying and administering London and other areas, shipping all able-bodied men to Germany to work as slaves, setting up concentration camps, and all of the horrible things they did in other occupied countries. Many highly placed ex-Nazis were still alive and willing to be interviewed.