Soldier of Orange

The film is about a group of students from Leiden, the Netherlands, amongst them Erik Lanshof (Rutger Hauer), Guus LeJeune (Jeroen Krabbé), Jan Weinberg (Huib Rooymans), and Alex (Derek de Lint). Robby Froost (Eddy Habbema) is a friend of Erik's, and Esther (Belinda Meuldijk) is Robby's girlfriend. Each of them happens to follow a different path and therefore has a different role in the Second World War, either as a collaborator or in the resistance. Part of the story is set in London, where Queen Wilhelmina (Andrea Domburg) has her residence. The students Erik and Guus fight alongside Colonel Rafelli (Edward Fox) and soldier Susan (Susan Penhaligon) of the allied forces in London.The film begins with a flashforward in the form of a newsreel with a voice-over. Queen Wilhelmina is accompanied by Erik arriving in the Netherlands from London shortly after the Second World War. After the newsreel the film starts in the late 1930s in Leiden, where freshmen undergo the humiliation of the initiation rites of their fraternity. Erik is picked out by Guus, the chair of the fraternity, who throws a bowl of soup over his head and injures him with the bowl. After this accident the two become close friends and Guus offers him a room in his private student apartment in the center of Leiden. In this house the students (Erik, Guus, Jan, and Alex) have a drink which confirms their new friendships.An English radio broadcasting interrupts the students in a tennis match and announces the declaration of war by the United Kingdom against Germany. In the beginning the students seem to take things lightly, the Netherlands will probably be neutral again, like in World War I. Jan and also Alex, who has a German mother, immediately join the Dutch army. Then German bombs start to fall, and Erik and Guus try to join the army but they are not accepted by a traumatized army officer. Shortly thereafter the Netherlands capitulates. Erik has an affair with Esther.Robby has a radio transmitter in his garden shed from where he contacts the Dutch resistance in London. He arranges for Erik to take a flight to London. The Jewish Jan, student boxing champ, gets into trouble by fighting with two anti-Semitic collaborators, who were bullying a Jewish salesman. Because of this Erik offers his place on the airplane to Jan, but during the pickup they get into a fight with Nazi soldiers, and Jan gets captured. Erik is able to escape.When Erik meets Alex during a military parade, he finds out he is now fighting on the German side for the SS. Later Erik is also captured. In prison he hears from Jan that "Van der Zanden" is the traitor in London. Jan is executed. Robby's radio installation is discovered and he is forced by the Gestapo to cooperate as a spy, because his fiancée Esther is Jewish.Erik and Guus try to flee to London again, this time on a Swiss boat and they get picked up by a Royal Navy ship. In London Erik meets Van der Zanden (modelled after general François van 't Sant) and tries to kill him, but he appears not to be a traitor but head of the Dutch Central Intelligence Service and a trustee of the Dutch Queen. Guus has an affair with the British soldier Susan. Erik and Guus agree with the Queen to pick up some resistance leaders who could play an important role in the Netherlands after the war. Guus is dropped on the beach and tricks himself into a party near the beach. Now Erik has an affair with Susan.Erik comes back to the Netherlands to pick up Guus and the resistance leaders. But Robby is with them on the beach and the Germans have followed the group who are about to escape by sea. Erik tried to warn them about Robby, but couldn't reach them. On his way to the beach Erik runs into Alex at a Nazi party close to the beach and dances ballroom tango with him in the middle of the party. Erik is able to flee from the party onto the beach and meets the others. When Robby sees that Erik knows about his collaboration, he flees. Then the group who tries to escape is under fire. The resistance leaders get killed, Guus escapes over land, and Erik is able to escape on the British ship and returns to London, and to Susan.When Guus meets Robby he shoots him in the middle of the street. Guus gets caught and is beheaded. Alex is fighting in Russia and gets killed by a hand grenade thrown by a boy he had insulted when he begged him for food. Erik becomes an RAF pilot and drops bombs over Germany.Later Erik is appointed as adjutant to the Dutch Queen, and accompanies her back to the Netherlands after the war is over, as shown in the newsreel in the beginning of the film. In the end Erik meets Esther again and finds that the Dutch have cut her hair short in anger at her and Robby's collaboration with the Nazis. She says she bears no grudge against anyone for this. Finally Erik celebrates the end of the war with one of his fellow students who also survived the war.

Question: What kind of dance did Erik and Alex do at the Nazi party by the beach?
Answer: Ballroom Tango