Paradise Lost: The Child Murders at Robin Hood Hills (1996)
Director: Joe Berlinger, Bruce Sinofsky. 150 min. Documentary.
Paradise Lost 2: Revelations (1999)
Director: Joe Berlinger, Bruce Sinofsky. 130 min. Documentary.
Paradise Lost 3: Purgatory (2011)
Director: Joe Berlinger, Bruce Sinofsky. 121 min. Documentary.
Multiple times, I've lost hope that movies are able to change anything or anybody, and I've accepted that they're merely a source of (sometimes smart) entertainment. But this was the first time I was definitively proven wrong. This documentary trilogy, made several years apart, changed how people thought about three youngsters accused of brutally murdering three schoolchildren (the "West Memphis 3"), and eventually got them out of prison after rotting in there for 18 years. These movies saved lives. Yes, we're talking 7 hours of film; but if you dedicate this amount of time, you will change too.
PS: The first episode got 96% on the Tomatometer. The second got 90%. The third got 100%, and won this year's Oscar for Best Documentary. Are you persuaded?