The Informer. The Tango Man appears

Was Annika's death an accident or murder? Zsolt learns of Annika's sudden death on the way to the British Museum. Symi, once a friend of Annika, asks Zsolt for her correspondence, but Zsolt wants to investigate immediately, flies to London, and meets Symi and her friend, Helen. At Club Tango Argentino they meet Marcel, their former boyfriend, and his partner, Joan, a famous Tango dancing couple. At Helen's party, Marcel wants to sexually provoke Symi, Zsolt confronts Marcel and, after a heated chase, is stabbed.
Symi and Helen, sweethearts, care for him and involve him in their act of love. Marcel provokes Zsolt, kidnaps Symi, and forces her to work for him as an informant. Zsolt and Helen's attempt to break Symi free is within reach, but Zsolt is knocked out by Marcel, L'homme Tango. He has faced a changed Marcel and meets his cousin John, who advises him strategically and can count on effective backup from his uncle.
The situation escalates into a deadly confrontation and tension mounts as Marcel, the Tango Man, challenges Zsolt to a duel. Will he be able to save Symi? Zsolt and John are prepared.