Inspired by Cahokia's mounds, planned settlement, palisade, and timber circle
The Thirteenth Season
A wooden calendar has cast a shadow for a month that should not exist.
What the party believes
The characters attend a sunrise program at Cahokia when a ranger called Morning Star notices an extra post standing in the reconstructed wood circle. Its shadow points between the marked seasons. By noon, a neighborhood appears beyond the park boundary where an empty field stood that morning.
The residents have documents, family photographs, and memories of living there for decades. Morning Star asks the party to help before officials arrive. Birds circle him in the shape of a figure found on old engraved shells.
Find out where the new neighborhood came from and stop the extra season from spreading across the floodplain.
Where the trail leads
- Measure the new post while crops around it race from seed to harvest and back again.
- Interview residents whose histories fit perfectly into gaps in local records.
- Enter a chamber inside the great mound that contains calendars for years that never happened.
- Discover that Morning Star placed the extra post before inviting the party to the site.
- Confront his winged ceremonial form as the thirteenth season begins replacing the present.
What actually happened
Morning Star is the priestly power represented in Cahokian imagery, preserved through the calendar. Earlier leaders used the timber circle to choose which possible season the city would inhabit, sending floods and failed harvests into discarded years.
The new neighborhood belongs to one of those discarded seasons. Morning Star wants to make it permanent, even if the current city is pushed into its place. The party must decide whose reality stays on the floodplain.
Where it can end
- Remove the extra post and erase the returned neighborhood again.
- Defeat Morning Star and merge the two seasons without his control.
- Make the thirteenth season permanent and help both communities survive the collision.
The history behind the story
Cahokia was the largest pre-Columbian settlement north of Mexico. It included many mounds, planned activity areas, a palisade, and a circular timber monument often called Woodhenge. The calendar that selects seasons is a fictional change made for the adventure.
Content notes
flooding, food insecurity, displaced communities. Change or fade any element that does not suit your table.