Final answer:
Charles Manson was obsessed with The Beatles' "Helter Skelter" because he believed it prophesied an apocalyptic race war, which influenced his actions leading to the notorious 1969 murders.
Step-by-step explanation:
The song that Charles Manson was obsessed with is "Helter Skelter" from The Beatles' 1968 White Album. Manson interpreted the song as a prophecy of an apocalyptic race war that he believed he needed to instigate. The actual content of the song, according to its writer, Paul McCartney, was about an amusement park slide, but Manson's twisted interpretation fueled his motivation for the infamous Tate-LaBianca murders in 1969. His belief that the song contained a hidden message is an example of how cultural texts can be misinterpreted with dire consequences.