The Red Pyramid - Rick Riordan
Ever since their mother's death, siblings Carter and Sadie have been near-strangers. While Sadie's lived with their grandparents in London, Carter has traveled the world with their father, the brilliant Egyptologist, Dr. Julius Kane.
Then one night they are reunited when their father takes them brings the siblings together to the British Museum, hoping at last to set things right. Instead, he unleashes the Egyptian god Set, who banishes him to oblivion and forces the children to flee for their lives.
Soon, Sadie and Carter discover that the gods of Ancient Egypt are waking, and the worst of them — Set — is after the Kanes. To stop him, the siblings must embark on a dangerous journey across the globe - a quest that brings them ever closer to the truth about their family and its links to a secret order that has existed since the time of the pharaohs...
Kane Chronicles, #1