In 1974, Los Angeles teenager Todd Bowden arrives at the doorstep of elderly German immigrant Arthur Denker, accusing him of being wanted Nazi war criminal Kurt Dussander.
Todd asks to hear detailed stories about his crimes, having recently become interested in the Holocaust.
Over the next months, Todd visits Dussander daily under the pretext of reading to him, all the while badgering him into revealing more details of his atrocities.
Todd soon forces Dussander to wear a replica SS Oberleutnants uniform and march on command.
When circumstances do not allow him to continue his killings, he picks a concealed spot overlooking the freeway and aims at people in passing cars with his hunting rifle.
At the hospital, Dussander shares a room with Morris Heisel, an elderly Jewish man and Holocaust survivor who recognizes "Mr. Denker" but cannot place him.
A few days later, Heisel realizes Denker is Dussander, the commandant of the camp where his wife and daughters were murdered in gas chambers.
Identifying Dussander as the man who he actually met, French confronts Todd, who responds by fatally shooting him.
He takes his rifle and ammunition to his hideout by the freeway and embarks on a shooting spree, resulting in his death at the hands of the authorities five hours later.