I've already put up the first chapter of Darkness Comes Before the Dawn, the full story of Drowning. It takes place about two weeks after the second chapter, Choices.
Summary: Everything went wrong in the battle. What should've been a victory is a terrifying defeat. Now the demigods, both Roman and Greek, are on the run. Finally, a quest is issued to find the four missing demigods of the Great Prophecy, including Percy. It is a quest that is destined to go wrong. They say that darkness comes before the dawn. That's assuming you survive the dark.
Go and take a look.