The Book of Secrets — David Michael Slater

The world was turning out to be not just a book of secrets, but a whole library full. Dexter and Daphna Wax have learned incredible secrets. Their mother was thousands of years old and on a Council devoted to destroying the First Tongue. And there are connivers, like Asterious Rash, who would do anything to learn Words of Power. They also know the Words were hidden in the Book of Nonsense. But now it's out of their hands, and they may not survive long enough to get it back. The twins might stand a chance of completing their mother's mission -- if they can get on the same page -- but danger looms closer to home than they ever thought possible. And the new secrets Dex and Daphna uncover are ones they never wanted to know.