After losing her right lung to cancer, Edie Littlefield Sundby became the first person in history to walk the entire 1,600-mile El Camino Real de las Californias mission trail through the mountain wilderness of Mexico and the Sonoran Desert, to Northern California. She experienced desert heat and cold, walls of cactus, sleeplessness, hunger, both physical and spiritual exhaustion, the dangers of wild creatures, and encounters with drug smugglers – and weeks with no water other than what a pack mule could carry. “The Mission Walker” is her first-hand account of the experience and struggles she endured, and the inspiration drawn from the old unmapped Spanish mission trail. Her story is both an adventure story and a reflection on the universal experience of confronting our own mortality. It is a story of what we will do when faced with the potential end of our life. What do we do with our time left on earth? And how much do we still really, truly want to live.