Throughout “The Flat,” shades go up, shades go down.

It’s an apt metaphor. Israeli filmmaker Arnon Goldfinger’s family didn’t talk about their experiences during World War II. So, when he discovers by accident that his grandparents maintained a friendship before and after the war with a leading Nazi official, it opens a window into a troubling past in “The Flat.”

The contemplative documentary about family secrets begins in Tel Aviv with the passing of Gerda Tuchman, Goldfinger’s 98-year-old, German-born grandmother. Family members help pack up her apartment and preserve family history, as a book collector mocks her collections of Shakespeare, Goethe and Balzac and a history of the Jewish people as subjects nobody reads anymore.

Goldfinger, like his siblings, learned little of family history growing up. But things take a curious turn after a commemorative coin featuring a Star of David on one side and a swastika on the other is found among the letters and photos stored away in boxes. Even more surprising is a notorious Nazi magazine and what’s inside it – a travel article on how the Tuchmans, at the behest of the German Zionist Federation, accompanied Baron von Mildenstein, a Nazi, and his wife to Palestine in the early 1930s.

Goldfinger’s research into von Mildenstein reveals anything but a garden-variety Nazi: In a film clip from the Nuremberg Trials, a glassed-in Adolf Eichmann mentions von Mildenstein by name as a mentor and SS propaganda minister who worked on “the Jewish Question.”

The Tuchmans and von Mildensteins shared a belief that Jews should live in Palestine. But correspondence and photographs make clear they became close friends. Surprisingly, Goldfinger learns after a friendly meeting with Edda, von Mildenstein’s daughter, that the friendship resumed after the war, when her father worked as a press officer for Coca-Cola.

If Goldfinger is dumbfounded and disturbed by what he has uncovered, his mother, Hannah, is indifferent. She doesn’t understand why the “third generation” needs to ask so many questions of the past, and thinks it would be impolite to let on that von Mildenstein was a Nazi when they meet with Edda in Germany.

Like Hannah, Edda also seems indifferent to the past. Jewish or German, that generation’s reluctance to know – or to hide – what their parents did or experienced during the Holocaust, captured in small and illuminating moments, may be what lingers the most after viewing “The Flat.”

the flat

3 stars

Director: Arnon Goldfinger

Running time: 97 minutes

Rating: Not rated, but PG equivalent for subject matter. In Hebrew, German and English, with English subtitles.

The Lowdown: A family member uncovers a surprising connection between his Jewish grandparents and a Nazi in this documentary.