From the introduction:
Beginner Box Bash: Ruins 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.
Having purchased information from a roving band of Varisian wanderers coming through Absalom, the Pathfinder Society has tasked the PCs with investigating a set of ruins in northern Varisia. Believing the site to be a lost Thassilonian outpost, the Society wants the PCs to bring back any artifacts relating to the ancient culture.