From highly acclaimed filmmaker Joe Berlinger (Brother's Keeper, Paradise Lost 1 & 2, Metallica: Some Kind of Monster)--one of the leading voices in American independent non-fiction cinema-comes Gray Matter, a riveting true-life mystery and perhaps the most baffling conspiracy story ever told about World War II. In the spring of 2002, Berlinger traveled to Vienna to witness the burial of the preserved brains from over 700 children who were experimented upon in a Nazi "euthanasia" clinic. Gray Matter chronicles the director's personal journey as he searches for forensic psychiatrist Dr. Heinrich Gross (notoriously nicknamed "the Austrian Dr. Mengele"), who allegedly participated in these mad-scientist trials for decades after the Holocaust and the end of the war. Along his path towards the unknown, Berlinger meets clinic survivors and other remarkable voices, each of whom has new light to shed upon this shadowy legacy and the nation that now grapples with its own denial. Is Dr. Gross alive? Is he in hiding? Should his advanced age and scientific aspirations be measured today against the accountability of his misdeeds? Raising provocative yet respectful questions of guilt, redemption and the ethics of mankind, Berlinger sorts out the twists in one of history's lesser-known, unsolved puzzles.