The Gatekeeper Trilogy Boxed Set

 is a hardcover collecting all three novels of the The Gatekeeper Trilogy book series. It was originally published on September 30, 2001 by Simon & Schuster.

Synopsis
Buffy Summers, teenage girl and vampire slayer, faces perhaps her greatest challenge yet. In the absence of an heir, the Gatehouse, a mystical prison for otherworld entities, is growing weaker. The fanatical Sons of Entropy will do anything to assure this, hoping to release not only the house's prisoners but also the monstrosities of the Hellmouth, over which Buffy's pleasant little town resides. The battle rages on two fronts — in Europe and in Sunnydale — but Buffy is not alone. She and her friends Angel, Xander and Oz, are determined to stop the Sons' leader II Maestro. But he will not take this threat lying down, and has enlisted the help of some of Buffy's oldest enemies...