Savaged Fallout: Redwood Towers

From the introduction:

Strange stories about the untamed north can be heard in the bars of New Arroyo and Klamath, where the tribals who live in the mountains and the evergreen forests come to trade. One such story caught your attention: a brave of a small tribe called the Chetcan, Brahmin herders and pelt hunters, had made mention of spotting a group of heavily-packed, green-skinned “demons” marching through the Red Wood, heading toward a set of ruins of the ancient world. After their passage, loud noises could be heard coming from the dilapidated building day and night…

Redwood Towers is an adventure for three to four players of Seasoned rank.