 "The Kane Chronicles" (2010-2012) focused on Egyptian mythology; "The Heroes of Olympus" was the sequel to the Percy Jackson series.Riordan also helped Scholastic Press develop "The 39 Clues" series and its spinoffs, and penned its first book, "The Maze of Bones" (2008).His most recent publications are three books in the "Magnus Chase and the Gods of Asgard" series, based on Norse mythology.