Inheritance is the fourth and final book in the Inheritance Cycle written by Christopher Paolini. The Inheritance Cycle was originally intended to be a trilogy, but Paolini has stated that during writing, the length of the third book grew, and the book was split into two parts to be published separately. Because of this, many plot elements originally intended for the third book are in the fourth book. Like its predecessor, Brisingr, Inheritance has a subtitle, The Vault of Souls.