Beate and Serge Klarsfeld have spent their lives tracking down Nazi war criminals and bringing them to justice. Now in their 80s, they continue their fight against a resurgent far-right movement in Europe. The film explores both their past work and their current efforts to combat fascism, featuring personal testimonies from fellow activists and family to presidents and Holocaust survivors. The film is also the story of a love affair between Beate and Serge; hunting partners, fellow activists, husband and wife, and parents, revealing both their courageous work and enduring love.