After being attacked by Empousai cheerleaders at his new school , Percy returns to Camp Half-Blood and learns about `` The Labyrinth '' , part of the palace of King Minos in Crete that , according to Greek mythology , was designed by Daedalus . After being attacked by empousai cheerleaders at his new school , Percy returns to Camp Half-Blood and learns about the Labyrinth ; part of the palace of King Minos in Crete that was designed by Daedalus .