A case that seems to come straight from a Hollywood film is taking place in Warsaw’s courts.

The son and widow of Wladyslaw Szpilman, The Pianist from Roman Polanski’s 2002 film, have taken the Polish writer Agata Tuszynska to court over a book she published 18 months ago, in which she accused Szpilman of collaborating with the Nazis and sending thousands of Jews to death camps.

Wladyslaw Szpilman was born in 1911 into a Jewish family in Sosnowiec, Poland. He started taking piano lessons and at the beginning of the 1930s moved to Warsaw, then Berlin, where he took lessons from the best teachers. Hitler’s rise to power forced him to return to Poland, where he continued composing.

With the German invasion of Poland in September 1939 Szpilman’s position as a pianist with Polish Radio was terminated, and he moved, with his family, to the Warsaw Ghetto where he continued to perform in restaurants.

When most of his family were sent to Treblinka, Szpilman managed to escape. With the assistance of the Polish underground he hid in an empty house. One day, when he left his hiding place to look for food, he ran into a German captain, Wilm Hosenfeld. The terrified Szpilman told Hosenfeld that he was a musician and the German officer led him to an abandoned piano where Szpilman played Chopin. Impressed, the German officer provided Szpilman with food and warm clothes.

At the end of 2010 Agata Tuszynska published a book based on the story of Wiera Gran, a well-known singer from the 1930s who performed in bars and clubs throughout Poland. Gran was also forced to move into the ghetto, but managed to escape in 1942. Even then, rumours claimed that she was collaborating with the Nazis. She fled Poland for Israel but rumours continued, and she left for France.

In meetings with Ms Tuszynska, Wiera Gran accused Szpilman of collaborating with the Nazis and being responsible for sending thousands of Jews to death camps while he served, so she claimed, as a Jewish policeman in the ghetto. The allegations caused outrage in Poland and especially among the Szpilman family, who demanded an immediate apology from Ms Tuszynska. When she refused, they took her to court.

Andrzej Szpilman, Wladyslaw’s son, said that Gran’s accusations had only one motive – jealousy. “My father never served as a policeman in the ghetto or collaborated with the Nazis. These are sick fantasies and the media present them as facts” he said. He added: “Wiera Gran was not a popular singer before the war. Only when she performed in the ghetto’s restaurants did she gain some popularity. Shortly after she escaped the ghetto rumours started about her collaborating with the Nazis. I know that she even performed in a cafe called ‘Mocha’, popular among German soldiers.

“After the war, nobody was interested in her any more, while my father gained popularity. She was jealous of my father’s success and tried to harm him with false accusations. Moreover, in 1946, after the war ended, my father published his autobiography, using his real name. Can you imagine him being a collaborator and not trying to hide his real identity? ”

Ms Tuszynska told the Polish newspaper, Gazeta Wyborcza, that she had only quoted Gran. “I stand behind the words in my book” she said. “I wrote this book on Wiera Gran trying to be as honest as possible and I wrote what she said about Szpilman. Should I change what she told me? Neither I nor Andrzej Szpilman were in the ghetto, where everything happened”.

Andrzej Szpilman, asked if his family might reach a compromise with Ms Tuszynska, responded: “For me she is not a human being. I am not prepared to deal with such people. I believe the court will make the right decision. I am only sorry that a part of the Polish media has repeated the accusations against my father as they appear in the book and launched a campaign against him in recent months.”