This book is a very good book. MY one criticism is that the Kindle Edition is more expensive than the Hardcover edition.
*****SPOLIERS***** The mark of Athena refers to Annabeth as expected. I thought mabye that Ricky would give an extra twist or two in referance to the 'revenge' of Athena. The twist at the end was very suprising. Annabeth goes evil!!! pity no Grover but Gleeson Hedge makes up for his lack. *****END SPOLIERS*****
I hope this has been helpful - get the Hardback edition!!!!!!!!!!