I didn't realize that it was book two when I picked it up, but that just meant that the action started that much sooner (although I had to figure out who everyone was). Oz, Angel and Buffy are touched by the paranormal, so they can travel the Ghost Roads, where spirits pass on their way to their final destinations. Many ghosts wander the roads because they are afraid of what that destination is. Breaches are opening and the villain (Il Maestro, not to be confused with The Master, whom I did confuse him with) wants to open the Gates of Hell through the Ghost Roads.
The Flying Dutchman makes an appearance and takes Giles on board.
The ending was a downer, and not because [edited] dies, but suddenly there's a way for humans to travel them.
I edited who dies, but let's face it, you know that that person has to come back to life in the next book. The series was still on the air at the time!