George C. Scott in Hardcore (1979)

Jake Van Dorn is a conservative business man and single father living in the midwest. When his only daughter Kristen goes missing on a church trip to California and the local authorities can't find her he takes it upon himself to locate her and in the process gets sucked into the seedy world of pornography.

MoviePosterShop.com

This film takes an unflinching look at a head-on collision between two completely incompatible factions of American society, and like fire and gasoline the results are explosive. Scott's performance in the film is raw and visceral, his frustration and anguish is palpable. This is Paul Schrader's second film as a director after having written Scorsese's Taxi Driver 3 years earlier. The two films share a gritty quality and bleak outlook.

This film is available on DVD. It's remained obscure most likely because of its subject matter which still remains taboo. The television trailer for it is above, uploaded to YouTube by robatsea2009.

Obscurity factor: 8 (largely unknown, available on DVD)