Rick Riordan – The Lost Hero is the first story in The Heroes Of Olympus series.
This novel was released on October 12, 2010.
The Lost Hero book description
After saving Olympus from the evil Titan lord, Kronos, Percy and friends have rebuilt their beloved Camp Half-Blood, where the next generation of demigods must now prepare for a chilling prophecy of their own:
Seven half-bloods shall answer the call
To storm or fire the world must fall
An oath to keep with a final breath
And foes bear arms to the Doors of Death
Now, in a brand-new series from blockbuster best-selling author Rick Riordan, fans return to the world of Camp Half-Blood.
Here, a new group of heroes will inherit a quest. But to survive the journey, they’ll need the help of some familiar demigods.