Taking place during World War II where Germany has successfully pushed through Western Europe and taken over Britain, but the German troops are pulled back to Russia leaving British fascists in charge. The film follows an Irish nurse Pauline who, despite having many friends in the resistance movements becomes enlisted by the Fascists to help their cause. As she collaborates with the Nazis, slowly Pauline become indoctrinated into the Fascist system.
When she meets up with some past friends, however, she is disillusioned and joins a resistance movement in Britain to drive out the fascists. Once the movements starts it soon grows ferocious and the actions of the resistance become similar to those of the Nazis.
The purpose of the alternative history in this film, while central to the plot, is not entirely clear. At first it seems that the filmmakers are using to film to show the evil and charisma of the Fascist party, but as the story progresses the themes because less clear. When the other forces in the war are portrayed equally as savage, it appears that war itself it the antagonist in the story.
The film was eight years in the making before it was completed and remains one of the longest productions in film history. A daring film yielding polarizing results, It Happened Here is a fascinating war film about one of the most important events in history.