A historical courtroom drama is perhaps Chinese cinema's best gift for the nation's first Constitution Day, which falls on Dec 4. Photo provided to China Daily

The film is a major breakthrough since the case hasn't been mentioned in Chinese mainstream media for decades. Hu Yaobang, a controversial name in New China's history, was the prosecutor in the trial and he is a major role in the film.

"Most of our team members are in their 30s, so it's a challenge for us to work with that unfamiliar part of history," Wang says. Shooting the film took some 45 days in unpleasant weather and tough living conditions last winter in northern Shaanxi, in the center of China's loess plateau, which was China's revolutionary base at the time of the story.

"But the conditions may have perhaps allowed us to experience what those revolutionary soldiers had endured," says Wang.

Yan'an was then the capital of the Shaan-Gan-Ning border region, the Communist Party's base to fight against Japanese aggression. When the murder occurred, the region's superior court had only functioned for two months, and its legal system was still not complete.