"The Ghost Writer" stars Pierce Brosnan as a former British prime minister closely resembling Tony Blair who hires a journalist (Ewan McGregor) to help him pen his memoirs.
But the writer quickly finds skeletons in the closet of his new boss, who is under investigation for war crimes for involving his country in CIA renditions of terror suspects, and in the process stumbles upon a global conspiracy.
The thriller is one of 20 films vying for the Berlinale's prestigious Golden Bear top prize and the most keenly awaited feature at this year's 60th anniversary event. The Hollywood Reporter called the movie "the hottest ticket in town."
Polanski, the Oscar-winning director of "Chinatown" and "The Pianist," completed the film at his Swiss chalet while awaiting possible extradition to the United States over a 1977 case of unlawful sex with a 13-year-old girl.
Critics who have seen the film have uncovered certain parallels to the embattled director's life, with a once-admired public figure who finds himself under fire and isolated.
Filmed in Germany, "The Ghost Writer" sees its prime minister in a kind of exile in the United States, fearing possible extradition to an international war crimes tribunal.
Polanski himself chose to flee the United States while at the height of his powers in Hollywood, unable to return without risking prison. The movie, based on British writer Robert Harris's bestseller "The Ghost," had been considered as the festival opener until organisers got cold feet.
"It might have been understood as a statement about something that we didn't want to get mixed up in," festival director Dieter Kosslick said in the run-up to the Berlinale's start Thursday with the Chinese drama "Apart Together."
Brosnan and McGregor, who were expected at the Berlinale to promote the film, told reporters in Paris this week that the 76-year-old Polanski was nothing less than a maestro.
"His energy is ferocious, he rules the set, keeps everyone on their toes," former "James Bond" actor Brosnan said. "He has an alchemy with the camera ... He's a taskmaster. You have to know your onions."
Polanski's long-time producer Robert Benmussa said the director's arrest in Zurich in September had created unexpected complications in finishing the film.
He kept the director abreast of the post-production through courier packages sent to his lawyer, who brought them to the director's jail cell.
"He is a director who is involved in everything on a film," Benmussa told The Hollywood Reporter.
The Berlinale runs until February 21.