(CNN) -- At first glance, "The Flat" might seem like an episode of "Hoarders," Israeli-style. The documentary film opens after an elderly woman dies in Tel Aviv. Her grandchildren assemble to clean out her apartment, packed with dusty books, vintage clothing (dozens of pairs of fancy gloves, for instance), enough purses to stock a department store, jewelry, mementoes and closets full of knickknacks. But buried among the detritus they chance upon something remarkable -- mysterious papers linking the grandparents to an important Nazi figure. How could such ardent Zionists, who left their native Germany in the early 1930s, have been involved with an SS official like Leopold von Mildenstein?
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Israeli director Arnon Goldfinger was shocked by what he found out about his grandparents
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His quest became the award winning documentary "The Flat"
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He says he faced a difficult decision with the project
What I found out was this journey, the Nazi (@placeholder) and his wife were accompanied by my grandparents," Goldfinger told CNN.