Heroes of Olympus, The, Book Three the Mark of Athena (Heroes of Olympus, The, Book Three) : Hardback : HYPERION : 9781423140603 : 1423140605 : 30 Nov 2012 : The third book in the Heroes of Olympus series will unite all of the beloved characters, but they number only six--who will complete the Prophecy of Seven? With a marvelous ship, fearsome foes, and an exotic setting, \"The Mark of Athena\" promises to be another unforgettable adventure by a master storyteller.