The Odessa File. The diary of a Holocaust survivor leads a journalist in 60s East Germany (Jon Voight) to become obsessed with tracking down a Nazi war criminal who never faced justice, and comes up against a secret society of former SS members known as "Odessa". This mid 70s conspiracy thriller has the grit and atmosphere you'd expect of a mid 70s conspiracy thriller, and even has future
Doctor Who alumni Mary Tamm in a major supporting role, but while interesting enough it's slow pace and 2 hour+ running time make it a long haul at times (or perhaps I've just been watching too many Hammer/Amicus horror flicks of late, which tend to be in and out in 90 minutes tops!
).