Dan Brown fans pining for a follow-up to The Da Vinci Code will have to rest their eager eyes for a while longer. The mega-hit author's newest novel will not hit shelves until at least 2007, more than a year later than originally expected. Suzanne Herz, a spokeswoman for publisher Doubleday, said she did not have a more specific date of publication. "My books are time-consuming to research and complicated to construct," Brown said in an email Herz provided to The Associated Press on Friday. "I am taking the time necessary to ensure that this new book is every bit as entertaining as The Da Vinci Code." The forthcoming book is said to revolve around Da Vinci Code star Robert Langdon and the Masons, a secretive fraternal organization. Brown has said its tentative title is The Solomon Key.