AP - They were both Holocaust survivors from Poland who suffered through unspeakable tragedies. But when director Roman Polanski and producer Gene Gutowski teamed up in the 1960s they never spoke of the war, preferring to focus on life by making movies and partying hard.

Even when the two reunited decades later for the 2002 Holocaust film the "The Pianist," they didn't talk about the horrors they had seen.

On Thursday, a new documentary about Gutowski's improbable wartime survival premieres at the Warsaw Film Festival, directed and produced by his son, Adam Bardach.

Gutowski didn't even speak about his past for years with his three sons, telling them the truth only when they were adults: that he was Jewish, that most of his family perished and that the name Gene Gutowski was an assumed identity that helped him survive WWII.

"For many years, I was living in absolute denial as far as being Jewish was concerned," Gutowski, 89, said in an interview at his home in Warsaw this week. "I just didn't wish to pass the burden of the Holocaust on to the next generation. It's very painful."

Slowly, he opened up. Finally he wrote a memoir.

"Dancing Before The Enemy: How a teenage boy fooled the Nazis and lived" is a joint journey in commemorating the lost family of cultured Jews from the eastern Polish city of Lwow, today the Ukrainian city of Lviv.

"It wasn't a secret that the family members were all lost," said Bardach, a 44-year-old based in Los Angeles. "It was just a question of how and why, and who they were as people."

Gutowski was born Witold Bardach in 1925 into a family of lawyers, doctors, concert pianists and army officers. They lived a charmed life of privilege until 1939, when World War II broke out, bringing first the hardship of Soviet occupation to eastern Poland, followed by a German occupation that spelled genocide for the Jews.

After his mother was sent to the death camp at Belzec, young Witold knew he couldn't survive if he stayed in Lwow. So he went to Warsaw, all alone at 15, struggling to pass as an Aryan.

Relying on evocative historical footage and interviews with Gutowski, the 65-minute film traces his life during the war until the liberation, when, thanks to knowing English, he worked as a counter-intelligence agent for the Americans tracking down Nazis in postwar Germany.

Today, he credits his knowledge of German and a huge dose of luck and chutzpah for his survival. Those traits gave the hungry teenager the courage to walk into German-only restaurants in Lwow, yell "Heil Hitler!" and sit down to a good meal.

Later he went to the work for the German Luftwaffe in Warsaw, stealing radio transmitters for the Polish underground, an activity that nearly got him killed.

When he was being hunted by the Nazis for stealing the radio equipment he was given shelter by his Polish girlfriend's mother, a dentist, who procured the documents of railway worker Eugeniusz Gutowski, who had died in an accident.

As he learned of his family's past, Bardach, formerly a Gutowski, took on his father's original name.

"I didn't want the Bardach name to end," he said. "I felt very proud to be related to the Bardach family. They were people of substance with incredible stories of bravery."

Gutowski, who is pleased at his son's name change, says that was not an option for him once he became known in the film industry.

His collaboration with Polanski began in the 1960s when he produced three of the director's now classic films, "Repulsion," ''Cul-de-Sac" and "The Fearless Vampire Killers." Despite being friends who speak Polish together, the two men never discussed their own wartime experiences, Gutowski said.

Polanski escaped the Krakow ghetto, assumed a false name to survive and lost his mother at Auschwitz.

Still, while working on "The Pianist," Polanski relied on Gutowski to help recreate Warsaw street scenes under the Nazi occupation and to cast actors, determining who should be a German, a Pole or a Jew. Only thin actors could portray starving Jews in the Warsaw Ghetto.

Gutowski remembers the pain that returned to both of them during the filming of certain scenes. In one, Nazi guards randomly forced old Jews to dance together to a street band, one of the sadistic ways they dehumanized Jews before killing them.

"I remember sitting there with Roman and we were both crying," Gutowski said. "It just brought back the horror of it all."