Percy Jackson and the Olympians; The Battle of the Laberynth and The Last Olympian - By Rick Riordan

If you liked the first three, you'll like these. If you didn't read the first three, well, read them first.

The last two have everything the first ones did, adventure, mythical beasts, battles, Olympians, but as the books go on, the writing gets, if possible, better. I read the last book in one sitting. The ending is hard won for the characters, but satisfying. Everything turns out basically well, but it gives the illusion of life after it, not a clean ending but much more realistic.

I adore these books.