"If Not Us, Who," a nuanced portrayal of the birth of the guerrilla Red Army Faction, sheds new light on a troubled period in Germany's past and is a strong contender for the top prize at the Berlin Film Festival.

Andres Veiel's first feature depicts the fiery and tragic relationship between writer Bernward Vesper and Gudrun Ensslin, who went on to become a key figure in the leftist group that carried out a campaign of kidnappings and murders in the 1970s.

Veiel told a news conference on Thursday he wanted to move away from the classic images of student protests, radical groups plotting and murders, toward the subtle sociological and personal factors that fueled this explosive political movement.

"These pictures were right, they were the catalysts, but you have to start earlier, with the families, the background, you have to go into the core of the private life," he told reporters after a well-received press screening.

"There are a lot of other films on this topic but they don't focus on the early story."

Also known as the "Baader-Meinhof Gang" after founders Andreas Baader and Ulrike Meinhof, the Red Army Faction grew from the left-wing student protests and anti-Vietnam war movements in the late 1960s.

Action-packed film "The Baader Meinhof Complex," graphically depicting the rise and fall of the RAF, was nominated for a foreign-language film Oscar two years ago.

Instead of focusing on the action, however, Veiel's film, which has its world premiere on Thursday, looks at how this political consciousness arose, with a particular focus on the conflict between the Nazi and postwar generations.

"These people wanted to change something, they were not satisfied in the 1960s, they came from a very limited home and wanted to reinvent themselves," said Veiel, who already made an award-winning documentary about the group called "Black Box BRD" in 2001. "This meant going onto new paths also politically."

PRIVATE TRAGEDY, POLITICAL THRILLER

As well as a political thriller, If Not Us, Who is a tragic love story.

For most of the film, Ensslin and Vesper do not appear as militants but rather as characters the viewer can easily identify with. They study literature, have affairs, set up a publishing house, discuss politics and have a child.

Yet as protests against the Vietnam War and various forms of oppression around the world escalate, Ensslin's own feelings of revolt grow, exacerbated by her partner's infidelity.

Ensslin is also driven by her fear of being found guilty one day of having stood by and watched injustice rather than taking decisive action -- something she reproaches her father for with respect to the Nazis.

She becomes increasingly attracted to the more radical approach of rebellious Andreas Baader, and gives up her family to join his pro-violence cause.

Veiel says he wanted to show the early Ensslin in all her contradictions, not just the tough militant and "Medea that coldly sacrifices her child" like in previous portrayals.

"She would not have gone underground, if the pain of giving up her son had not been so great, because then, it really has to be for a big solution...then it must be about world revolution," he said. "In this respect, the private is very much linked to the political."

Veiel says the film raises questions that are still valid, just in a different historical context.

"We have problems in this world from the climate disasters to the next financial crisis," he said. "This motto 'If not us, who?' is still valid today, we have to get active in so many issues, so this is a film also about the present."

If Not Us, Who is one of the 16 films vying for the top prize at the 61st international Berlin film festival, which culminates with the awards ceremony on February 19.