Y - The Sword of Light

David was just going home from school, until he wasn't anymore. Okay, let me elaborate, he fell into a cave, went into a portal, and ended up in an abandoned island seemingly in the middle of the 7th dimension (there are only 3 dimensions in this book, and this is not about dimensions, and I meant to say "the middle of nowhere", but you get the point) that is in the middle of a massive civil war. What will he do about it? How will he face his problems, and stop the war? And most importantly, how will he get back?