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 figurehead, 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 command: 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. From Goodreads.

Rick Riordan continues to write books that I just can't put down. There have been a couple of nights that I have been very tired and decided to go to bed and read for just 5 minutes. Hours later I am still reading. There is a lot going on in this book: romance, battling giants and gods, and also trying to find out why friends act like the enemy in between. This book ends in a cliffhanger, I am glad I have the next one coming from the library soon.

This book qualifies for:
Goodreads 2013 Reading Challenge
Serious Readers 2013
Tower Teams Read 2013-2
2013 Paranormal Reading Challenge (demigod)
2013 Sequel Reading Challenge
2013 Mammoth Book Challenge