Professor Caligari and his carnival comes to town. Not at all original. But once you start reading, the not-well thought out Caligari becomes secondary to the Scoobie gang's dynamics. Buffy and friends (plus Cordelia) have a wonderful rapport with each other. The gang must solve the puzzle of why Sunnydale classmates are acting strange. Of course, it's the carnival, which steals souls by making the funseekers act out their worst deadly sin (out of the seven, and the book makes sure you remember there are 7 deadly sins by having the bad guys have the number on them somewhere, like on their cloths). Cordelia is hilarious as a greedy would-be robber. Buffy is all of 16, proud to be the Slayer and thinking pretty much only about smooching with Angel. Angel has some lusty (PG-13) thoughts about Buffy, though, so you really feel the age difference between the two.
Also, if you wondered how the human families of the vampires (who were once Sunnydale citizins) Buffy slays cope with the disappearance of a loved one, you'll get a partial answer here.
Some spelling mistakes, and luckily no retconning, to include Dawn. I found it a good read, and I like the Scoobie interaction.