The Black Reckoning (The Books of Beginning, #3)

The final book in the bestselling Books of Beginning trilogy that began with "The Emerald Atlas," which the "New York Times" called "a new Narnia for the tween set."
The adventures of siblings Kate, Michael, and Emma come to a stunning conclusion when they must find the last Book of Beginning--the Book of Death--before the Dire Magnus does, for when all three books are united, their combined power will be unstoppable.
Soon Emma is on a journey to places both worldly and otherworldly, confronting terrifying monsters and ghosts, and what is darkest within herself. As the fabric of time begins to fray, she becomes the final piece of an extraordinary puzzle. Only if she can master the powers of this most dangerous book will she, Kate, and Michael be able to save the world from the dramatic, deadly final confrontation between magical and ordinary people that the Dire Magnus has in store.