NofS is a paranormal mystery. Someone in London is recreating the murders of Jack the Ripper. Rory, a new American boarding school student with the new ability to see and interact with ghosts, is pulled into a ghost police task force in order to aid the investigation - all the while dealing with school, friends, boys, and the ever-increasing "Ripper Mania" that engulfs the area as the people await more murders. It's a thrilling adventure, often funny, and a great commentary on the celebrity status of monstrous people.
I loved it as much as I did the first time I read it.
The ending did pick up, however, and there will be a third installment to the series. I hope that the third book is more like the first. I've recommended NotS to many students and they've all come back saying that they loved it. I just hope they appreciate the sequel as well and will stick around for the next book.