The Kane Chronicles: Red Pyramid by Rick Riordan

The Red Pyramid is a great book about 2 siblings, Carter (14) and Sadie (12 ) Kane. It's set mostly in the U.S. but also in other places. They were separated at a young age. Carter lives with his father and wakes up not knowing where he is, or what day it is. Sadie, on the other hand, has some mates to hang out with and lives with their grandparents. Their mother is deceased. And then their father basically goes ballistic trying to find a way to bring her back to life, and one of his many attempts was banished to the Duat, the Egyptian underworld, and upon trying to save him, Carter and Sadie encounter many difficulties.

Rick Riordan does a great job of making the book historically and mythically correct. And in part of making this such a spectacular book, he makes it very similar to his other series, Percy Jackson and the Olympians, by putting in the gods, the children of the gods, and so forth. He also is very good at adding a sense of humor and drama in the story which is always twice the laugh when there's a sibling rivalry