Percy Jackson author Rick Riordan headlined a charity reading event with Maximum Ride author James Patterson last night. Riordan revealed secrets from the next installment of the The Heroes of Olympus series, The Son of Neptune.

Percy Jackson will definitely be back, along with Tyson the Cyclops, Grover Underwood, three new demigods, and a bulletproof elephant. He added: “there are other reasons besides Percy that the book is called The Son of Neptune.”

Follow this PDF link for a sneak peek of The Son of Neptune.

A banner decorating the walls revealed artist John Rocco‘s cover for the new book (pictured). Fans were treated to a reading with Percy and gorgons from The Son of Neptune.

During the Q&A session, Riordan announced that the final book in The Kane Chronicles will be released in spring 2012.