The Next Generation

Everything was fine. Back to normal.
Until a threat rose against Olympus, Tartaurus was slowly rising. Monsters couldn't die, the earth would restrain them from going back to 'The Place' but along the way, new monsters are discovered. More that demigods can't kill with their original weapons.
The next prophecy is released after years of the curse.

Cecil, Lou Ellen, Nico, and Will are up to an challenge no demigod ever completed.
Something that no demigod survived.
They must retrieve the arrows of Legend that can only kill the unidentified monsters.

Disclaimer: I do not own PJO or HOO. All right to Rick Riordan!