The famed Canadian explorer David Thompson, one of the word's greatest explorer-mapmakers, left a mystery in his wake in the period of time he spent developing the fur trade in northwestern Montana, northern Idaho and northeastern Washington (1807-1812) - the location of Saleesh House along what is now called the Clark Fork River in northwestern Montana - near the explorer's namesake town of Thompson Falls, Montana. In this book of exhaustive research and field word, travel along with author Carl Haywood as he follows Thompson's travels through Montana with brief looks at the journey along the way. Seeking an answer to the fundamental question of where, exactly, Saleesh House was located, Haywood takes the reader step-by-step through the hardships and peril Thompson and his voyaguers faced. Travel the same routes Thompson mapped using Google Earth coordinates or drive many of the routes using Carl's milepost map. Along the way you will learn about beaver, caches, canoe making and the value of trade goods. Based on Thompson's journals, the author, himself a retired professional forester, follows Thompson's day-to day-travels and the incredible challenges and hardships he faced. Traveling by foot, horseback and canoe, eating dogs and horses to avoid starvation, he and his little brigade of French-Canadian voyageurs, Indian hunters and guides, explored and mapped the upper Columbia River watershed from its headwaters in British Columbia to where its headwaters are discharged into the Pacific Ocean.