The Titan's Curse picks up where The Sea of Monsters left off: Percy Jackson and his friends Annabeth, Grover and Tyson (plus some others) are trying to stop Kronos from rising and wreaking havoc on Humanity. New book, new quest, and for Percy and his friends there are plenty of moments that they have to rely on their belief in themselves, use their various gifts and trust each other to get out of sticky situations. I've liked all the books in this series, and I'm continuing to learn more about the Greek myths through my foray into the world of the Half-Bloods.
If this review seems really short, that's because it is. I think that Riordan does a great job at keeping people invested in his characters, his storylines, and the development of the overall experience of reading these books. Every character is memorable, from Blackjack to Percy's mom, and every character gives Percy something he needs in order to succeed.