Apt Pupil (1998)

Todd Bowden is learning about the Holocaust in high school, and recognises an old photograph of a concentration camp officer as an old man in his neighborhood. He confronts the man, Kurt Dussander, with his knowledge. Obsessed with the atrocities Dussander committed during the war, Todd begins to blackmail the old man: in exchange for the teenager's silence, Dussander must reveal his evil past. As Todd probes the old man's buried memories, indications of his evil begin to re-emerge. The two begin a game of psychological warfare that spirals out of control; and Todd is pulled into a dangerous fascination with Nazism that threatens his academic and personal life.