From the introduction:
Beginner Box Bash: Terrors is a Pathfinder RPG Beginner Box demo adventure for 4–6 Beginner Box characters of 1st level. It is meant to be run as part of the Beginner Box Bash special event, but can be run as a stand-alone demo of the game at other events as well. Players are encouraged to use the provided pregenerated characters, but may create their own 1st-level player characters if time permits at your event. Aside from the map, everything you need to run this demo can be found in the Pathfinder RPG Beginner Box.
The player characters are sent by visiting Pathfinder Society Venture-Captain Sheila Heidmarch from Sandpoint into the Varisian town of Galduria to investigate rumors of an undead uprising. There, they must question the townsfolk before venturing into the cemetery late at night to confront the menace head-on.