Greil Marcus is one the leading Dylan biographers and this book-length work of his engages a particularly murky part of the artist's life: the days of the Basement Tapes, that period of time in 1967 where Dylan recorded extensively and secretly with the Band. The Old, Weird America: The World of Bob Dylan's Basement Tapes is actually an updated edition of Marcus' work Invisible Republic, which was first released in 1997. This newly titled edition has a new introduction and an updated discography; whether that warrants another purchase is up to you.
What isn't a question is whether or not to attend Marcus's reading tomorrow at San Francisco's Vesuvio. Marcus is one of rock's most important scholars. No one should miss an opportunity to hear him speak.