In Search of the Shadow People by Brian Jacob

In 1884, an expedition of 65 hunters, led by a retired Colonel and guided by Indian trackers, set out into the wilderness to find a mysterious tribe of Indians known as "The Shadow People". Only one returned. Now, 30 years later, an Indian tracker named Waha Tankany tells the story of what happened to the expedition, and how it relates to Ishi, the "Wild Man of Mill Creek".