The Mark of Athena (The Heroes of Olympus, Book 3)

The third book in the Heroes of Olympus series, The Mark of Athena reunites Percy, Hazel, and Frank from Camp Jupiter with Jason, Piper, and Leo. Together, the six demigods must work to defeat the giants released by Gaea, the Earth Mother. However, the Prophecy of Seven calls for seven heroes, leaving the question of who will complete it unanswered. The group must cooperate despite their Greek and Roman backgrounds and sail together to an ancient land to find the Doors of Death. Much of what the prophecy demands remains unclear. With old and new allies joining forces, a remarkable ship, powerful enemies, and an unfamiliar setting, the demigods face another adventure in their ongoing quest.