By Laura Koran, CNN

(CNN) - How many people would lay down their lives for a stranger?

It’s the question at the center of the new documentary “Besa: The Promise,” which premiered last weekend at the San Francisco Jewish Film Festival.

The filmmakers’ answer: “Albanians would.”

During one of humanity’s darkest chapters, when millions of Jews, gays, communists and racial minorities were rounded up across Europe, many Albanians put up a fight to save complete strangers.

They risked their lives to shelter displaced Jewish families under Italian, and later German, occupation during the Holocaust. Many in the small, predominantly Muslim country in southeastern Europe took refugees into their homes despite the risks and the cost, passing their guests off as family members to keep them safe.

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At the core of this effort was a concept called “besa,” an Albanian code of honor that holds a person’s oath as sacred.

Under besa, a guest in one’s home must be protected at all cost. The code is uniquely Albanian and is cited in the new film as the main reason that Albanians opened their borders and their homes to displaced Jews when many others in Europe turned them away.

The code is fueled in part by the tenets of Islam under which saving a life is a blessed act.

Until recently, this chapter of history remained relatively unknown, hidden by the decades of isolation that Albania fell under following World War II.

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“Besa: The Promise,” which will be shown in different parts of the country in coming weeks, tells the story of Albanian rescues by focusing on the overlapping journeys of two very different men.

The first is Norman Gershman, a Jewish-American photographer who for the last decade has photographed many of the Albanian Muslims who joined the effort to shelter Jews. He has traveled to Albania to meet with them or their surviving family members, documenting their tales of heroism.

The film’s second protagonist is an Albanian shopkeeper named Rexhep Hoxha, who was born after World War II but has struggled for decades to fulfill an oath that his now-deceased father swore in the 1940s.

Hoxha’s parents sheltered a Jewish family during the Holocaust. When members of that family fled to Israel, they left behind a set of religious books, which the Hoxhas promised would be returned to them one day.

But Hoxha never saw them again.

Lost to history

Albania is Europe’s only majority-Muslim country, and its Jewish population before the war was about 200 people.

To some, those facts may make it even more surprising that Albania succeeded where the rest of Europe failed.

According to Yad Vashem, the Israeli museum that holds the world’s largest repository of documents and information related to the Holocaust, there is not a single known case of a Jew being turned over to Nazi authorities in Albania during its occupation.

Incredibly, Albania’s Jewish population actually grew during World War II.

The reason so little is known about Albania’s unique role during the Holocaust has a lot to do with the country’s post-war history. Once the war was over, Albania fell under communist control and spent the next half-century behind the Iron Curtain.

Families who risked everything to save lives in the 1940s are only now getting recognized for their contributions.

'The documentary gods'

Rachel Goslins, who directed the documentary, is as familiar as anyone with the history of the war.

In her first short film, “Onderduiken,” she recounted her family’s ordeal hiding from the Nazis in the Netherlands. Yet Goslins said she was “gobsmacked” when she first heard about Gershman’s discoveries in Albania.

“It just seemed like such an important piece of history,” Goslins said. She was even more amazed when she and her crew came across Hoxha.

Hoxha’s quest to return the books that were placed under his father’s protection brings the story of what happened decades ago into recent times, illustrating how the principles of besa have endured.

When she heard about Hoxha’s mission, Goslins said she thought that “the documentary gods have dropped a gift in your path.”

The film takes Goslins and her crew from Albania to Israel, charting Hoxha’s commitment to a promise he inherited from his father and his fear of passing it on to his son. Until he finds the family that his parents' sheltered during the war, he continues to carry a burden.

'We did nothing special. It’s besa!'

For some in Albania, the recognition they’re starting to receive for their Holocaust heroics has come as a surprise. The concept of sacrifice is so deeply rooted in Albanian culture that many do not understand why they are considered unique.

Time and time again, when Gershman visited the families of Albanians who had sheltered Jews during the Holocaust, he found people who were quick to downplay the significance of that act.

Gershman recalls how one man, whose parents had been involved in the effort to save Jews, said to him, “So what? Anyone in Albania would have done the same thing. We did nothing special. It’s besa!”

The concept stipulates that a person must put his guest’s safety above that of himself and his family. One Albanian man told Gershman, “I’d sooner have my son killed than break my besa.”

Gershman said, “Anyone in need, if they knock on your door, you have an absolute obligation to save them, to take care of them, irrespective of if they’re friends, enemies, whatever."

The lessons of besa

The makers of “Besa: The Promise” said they see the film as a lesson in interfaith cooperation. “Seeing Muslims as heroes, and seeing them as heroes to Jews, is not a particularly common story in our world,” Goslins said.

That’s something she said she hopes she can change.

It’s a message that has become a mission for Gershman, whose collection of photographs from Albania has been exhibited around the world and who has published a book called “Besa: Muslims Who Saved Jews in World War II.”

Gershman takes the stories he heard in Albania to middle and high schools in the United States. He said he hopes to introduce the concept of besa to a new generation, thousands of miles from Albania.