floyd merrell 
Enigmas [EPUB ebook] 
Gold Fever, Space-Time Warps, Sierra Madre Magic

Four married couples from the southwest search for Spanish treasure in northern Mexico, guided by a peculiar map. They meet strange four-dimensional visitors from another world, Tarahumara people with a unique philosophy of life, local bandits roaming the area, narcos ready to kill any and all outsiders, and suspicious police and military personnel. Yet, they become enchanted by the vast Sierra Madre range, they find treasure that exceeds their wildest dreams, and unfortunately they begin squabbling over the take, until the alien visitors sequester most of it. Back home, they make amends, but soon realize their adventure, bizarre to the extreme, will continue haunting them to the end.