Updated: Check out the next book in the series: The House of Hades. Previously, we have seen the official cover art of The Mark of Athena as it was released online. A few days after, Rick Riordan's official website has also released the official synopsis of the said book, together with the official number of page count, more or less for the hardbound edition.
As revealed, The Heroes of Olympus: The Mark of Athena would be 608 pages (according to Amazon, but Rick Riordan's site said it was 580 pages) all in all and would be released on October 2, 2012. This is quite a good news since it will be a lot thicker compared to The Son of Neptune's 544 pages (hardbound) and The Lost Hero's 576 pages. I was a little sad when the second book was shorter than the first one, because I am a little OC about page counts, especially to serial books and I expected each succeeding books would be thicker, if not the same.
Read on for the official synopsis of The Mark of Athena by Rick Riordan:
Annabeth is terrified. Just when she’s about to be reunited with Percy—after six months of being apart, thanks to Hera—it looks like Camp Jupiter is preparing for war. As Annabeth and her friends Jason, Piper, and Leo fly in on the Argo II, she can’t blame the Roman demigods for thinking the ship is a Greek weapon. With its steaming bronze dragon masthead, Leo’s fantastical creation doesn’t appear friendly. Annabeth hopes that the sight of their praetor Jason on deck will reassure the Romans that the visitors from Camp Half-Blood are coming in peace.
And that’s only one of her worries. In her pocket Annabeth carries a gift from her mother that came with an unnerving demand: Follow the Mark of Athena. Avenge me. Annabeth already feels weighed down by the prophecy that will send seven demigods on a quest to find—and close— the Doors of Death. What more does Athena want from her?
Annabeth’s biggest fear, though, is that Percy might have changed. What if he’s now attached to Roman ways? Does he still need his old friends? As the daughter of the goddess of war and wisdom, Annabeth knows she was born to be a leader, but never again does she want to be without Seaweed Brain by her side.
Narrated by four different demigods, The Mark of Athena is an unforgettable journey across land and sea to Rome, where important discoveries, surprising sacrifices, and unspeakable horrors await. Climb aboard the Argo II, if you dare. . . .
Similarly, Amazon has their own intriguing version of the book's synopsis, which focused more on the seven demigods:
In The Son of Neptune, Percy, Hazel, and Frank met in Camp Jupiter, the Roman equivalent of Camp Halfblood, and traveled to the land beyond the gods to complete a dangerous quest. The third book in the Heroes of Olympus series will unite them with Jason, Piper, and Leo. But they number only six--who will complete the Prophecy of Seven?
The Greek and Roman demigods will have to cooperate in order to defeat the giants released by the Earth Mother, Gaea. Then they will have to sail together to the ancient land to find the Doors of Death. What exactly are the Doors of Death? Much of the prophesy remains a mystery. . . .
With old friends and new friends joining forces, a marvelous ship, fearsome foes, and an exotic setting, The Mark of Athena promises to be another unforgettable adventure by master storyteller Rick Riordan.
After having the last two books surging with a lot of male central perspective, feminists will be happy enough to finally read the series in the dominance of one of its major female characters, Annabeth. The story was after all about the Mark of Athena, who mothered Annabeth. Now, I am really happy about this series -- with the thicker book spine and synopsis and all.