The Lost Hero (Heroes of Olympus Book 1) - Rick Riordan

CAMP HALF-BLOOD is the only place for children of the Olympian gods to live. Where else can they fight monsters and practise archery with flaming arrows and explosives?

But Camp Half-Blood's latest recruits - Jason, Piper and Leo - haven't been brought here for fun.

A major problem has arisen.
Hera, Queen of the Gods, has been imprisoned.
They are the chosen ones to save her from great evil - with only four days to complete their quest.

And that's not all. Percy Jackson, hero of the half-bloods, is missing. The second great prophecy has begun.

But the half-bloods have no idea how many enemies they've awakened. This is a war they cannot win . . .

Can they?