The Fleabirds are a group of people indigenous to North America who have rejected the collectivism and sedentary lifestyle inherent in the Cosmic Era. Rather than living in the gleaming arcologies, steaming geofronts, or the great heaps of the urban rims and favelas. Rather, they live in caravans that travel the countryside of the continent.
The PCs see a large oak tree, a curious species of yellow and black butterflies swarm around it. Upon further inspection they find that the tree is hollow and that there is an underground cave in it from which the butterflies appear. Will they inspect this strange cave?