The Last Olympian
★★★★☆
Best book of the series - it's fast paced and exciting. Percy is aided in his quest to save the 'gods' of Olympus by Annabeth, the daughter of Athena, Grover, the satyr, as well as many other sons and daughters of the 'gods'.
Their travels and adventures take them to the Underworld, across the Sea of Monsters, and through the Labyrinth, all the while facing monsters and characters from ancient mythology. Riordan's characters are well crafted and likable, witty and quirky and they are again here in Last Olympian.
Other fantasy books I'd recommend are the brilliant time travel adventure 'Godstone' and 'Mariah Mundi':
GODSTONE - THE KAIROS BOXES