The Book of the Dead is a grimoire, a magical text containing all the lore of necromancy and counter-necromancy collected by the line of the Abhorsen.
It is studied by the Abhorsen-in-waiting as she or he learns about Death and the Dead, and the magic (both Charter and Free) used to deal with them.
It is bound in pale green leather and held shut by silver clasps which are covered in Charter marks to bind, blind, close and imprison. Only a person with an innate talent for Free Magic and necromancy may open it and only a person with an unsullied Charter Mark may close it again.
It is one of the 3 inheritances of the Abhorsen.