Dan Brown, famed author of "The Da Vinci Code" is slated to appear in the fourth installment of BookCon, an annual fan-based show that will be held next June. Producers of BookCon, ReedPop announced Thursday that popular young adult authors Cassandra Clare, Shannon Hale and Danielle Paige are also expected to attend the event. Previous speakers have included Amy Poehler, John Green and Mindy Kaling.