From the publisher's website:
Aces High: New Mexico, Dark Days in the Land of Enchantment, is a companion book for Chaosium‘s Aces High BRP supplement. Aces High: New Mexico is split into two sections; the first section is concerned with historical, geographical and societal issues that will allow the Master to explore some of the land of New Mexico during the appropriate period. The second section is the "Incident at Alice" scenario which will allow the players to interact with some of the people and creatures that live here.
In the scenario the characters will be involved in a bank raid, will chase an Apache outlaw across rugged terrain, be led into a deadly supernatural trap and meet a powerful Diabolist with an army of walking dead. Along the way they will begin to learn of the supernatural entities called the Kachina, sacred, mythical spirits of the Pueblo dwellers religion. The Puebloans themselves have a long and, at times, dark history. Some of which also waits to be discovered in one of their forgotten, ancient and holy sites.
The characters may begin to understand that not all Native Americans are the same. Being able to tell the difference between the thoughtful, artistic Puebloans and the warlike, aggressive Apache will give the characters some insight into the many divergent philosophies that are endemic of the native populations. In the end, learning this difference may be the weapon that allows the characters to succeed or fail in their quest.
Aces High: New Mexico has been designed to be a challenging adventure for mundane Aces High characters with some form of Otherworldly help, but could also be run for characters with their own Otherworldly abilities.