Metallica and Master of Puppets really helped shape the style of heavy metal music and were pioneers in the genre. Metallica's sound has changed over the years, but they always stayed solidly in the space of heavy metal. Master of Puppets is undisputedly one of the greatest heavy metal records of all time. The Story of Metallica's Master of PuppetsEven though Metallic showed a little of their affinity for melodic metal on Master of Puppets, a lot of this record was still pure thrash metal. "A fan made documentary that compiles hours of footage which tells the making of Metallica's third studio album, Master of Puppets," the movie's synopsis states in IMDb.