The Beach Boys and the Satan is a 1997 German documentary which definitely DOES NOT deliver on the title. The title leads you to believe it's going to be one of those Christian type exposes' of the evils of rock music. Instead the film is a recap of The Beach Boys career centering around Brian Wilson. Finally, at about 2/3 of the way into the movie the filmmakers discuss Dennis Wilson's brief association with Charles Manson. Then the film continues on with the history of The Beach Boys. Near the end of the documentary, the movie goes back to Manson and his followers. The Beach Boys and the Satan includes interviews with Brian Wilson, Kim Fowley, and Don Was. While the Brian Wilson interviews are fairly interesting, the Manson material is mostly a rehash of well known facts and I believe was only included so the title might peak viewers interest.
