4th part of the fantasy bestseller series. The army of Kronos is growing stronger! Now Camp Half-Blood is no longer safe from it, as Daedalus' magical labyrinth has a secret exit right in the camp. It's unimaginable what will happen if the Titan and his allies find their way there! Percy and his friends must prevent this at all costs. Fearlessly, they embark on a journey into the unknown, down into the underground labyrinth that constantly changes its shape. And around every corner, new dangers await...