Cirque de Lune

Once a year this circus shows up somewhere random in the world, occasionally the same place twice but rarely.
Every time it comes at least one person disappears with it as it leaves. Nobody knows why or where they go. Some say "the circus runs away with them instead of the other way around."
If you're a normal person here you have one goal before it's too late.
That goal?
Figure out that the circus is taking people and adding to its staff and escape without becoming one of them.
Though usually those who realize become one of them.