Carnival of souls - Nancy Holder

There is definitely something not quite right about the Travelling Carnival. Perhaps it's that no one can recall the arrival of its hard-to-miss caravan of old-style wagons, countless performers, and horse-drawn carts. Maybe it's the creepy calliope music that tirelessly beckons visitors. And no-one who visits its Hall of Mirrors seems to come out the same as they went in. Somehow they have different personalities. When a once-shy pair of homely twins begin to parade around Sunnydale High like divas, Buffy and the others decide to investigate the Carnival firsthand. But soon it becomes apparent that the price of admission is higher than they imagined. Willow is consumed by envy, Cordelia by greed, and Xander by gluttony. Angel reveals a dangerous new persona, while dark anger rises in Giles. More powerful still is the blinding pride that threatens to overwhelm Buffy and destroy all those she loves...