L. Frank Baum is one of the great children's authors of the early 1900s. He's most famous for his wildly popular and critically acclaimed The Wizard Of Oz series. Baum is widely respected for his great sense of imagination and his understanding of morality.
Baum spent many years trying to shake off the popularity of the Oz books, as his real passion was writing adult books, of which only 4 of his were ever published. Another 4 never saw the light of day, mostly due to Baum's financial troubles. The books were titled Our Married Life (1912), Johnson (1912), The Mystery of Bonita (1914) and Molly Oodle (1915). Little is known about the plots of these works. When Baum ran out of money to continue writing these books, he would lean back onto his precious Oz books for financial support. Publishing companies would often reject these works, choosing to continue making him milk out the Oz books instead.
The 4 unpublished books remained unknown until Baum biographers discovered file folders and paperwork for the novels, but the actual manuscripts were missing. It is completely unknown what happened to the novels and it remains one of the great literary mysteries to this day. One commonly circulated theory is that Baum's wife may have destroyed the novels in a fire.