Boys Town (1938): Spencer Tracy won his second Oscar (the first man to win best actor Oscars back-to-back) playing real-life Father Flanagan, founder of a community for poor and at-risk youths, whose belief "There's no such thing as a bad boy" is challenged by his experience with hoodlum Whitey (Mickey Rooney). While the film seems a bit sentimental and hokey today, it does pay tribute to a genuine advocate for reform and welfare.

Dead Man Walking (1995): Writer-director Tim Robbins guided then-partner Susan Sarandon to an Oscar in her role as real-life nun Sister Helen Prejean, who is asked by a death row inmate, Matthew Poncelet (Sean Penn) to help with his appeal. This is no John Grisham-type legal thriller, though, it's an absorbing, moving and stimulating examination of two very different people.

The Exorcist (1973): While it's notorious for its horror and gross-out elements, this film adaptation of William Peter Blatty's novel about two priests' efforts to save young Regan (Linda Blair) who seems to be demonically possessed is also an examination of good and evil and faith.The age makeup used on Max von Sydow is even more impressive than that on Linda Blair: then in his 40s, he looks pretty much like he would four decades later. Jason Miller plays the younger priest, uncertain of his faith but dedicated to his task of saving the girl.

The Apostle (1997): Actor Robert Duvall hasn't worked behind the camera much but the results tend to be interesting: his first feature, Angelo My Love (1983) was about the world of American gypsies.Duvall writes, directs and stars in this labour of love, which he also funded - it took a long time to pull together but turned out to be worth the effort. It's a complex character study, looking at the turbulent personal and professional life of a Pentecostal preacher without demonising or lionising him. Sonny is a sincere but flawed man and Duvall's portrayal of him is a memorable one.