The Mark of Athena by Rick Riordan (The Heroes of Olympus #3)
start, the peace with the Roman camp they were hoping for is long gone and they are planning on going after them.
They are on a ship, made by Leo, trying to come to the ancient land, but of course, it never goes smoothly for the heroes.
Annabeth has a quest of her own to complete, she has to follow the Mark of Athena and find the statue that was lost for centuries. She is hoping that it will help bring peace between the camps, but the mission is not easy.
It's my favourite in the series so far- Percy and Annabeth are finally back together. :) And that cliffhanger at the end, omg!