In the 1980s, a neurologist named Francisco Lopera travelled on horseback into the mountains seeking families with symptoms of dementia. For centuries, residents of certain villages near Medell­n had suffered memory loss as they reached middle age, going on to die in their fifties. Lopera discovered that a unique genetic mutation was causing their rare hereditary form of early onset Alzheimer's disease. Over the next forty years of working with the 'paisa mutation' kindred, he went on to build a world-class research program in a region beset by violence and poverty. In VALLEY OF FORGETTING, Jennie Erin Smith brings readers into the clinic, the laboratories, and the Medell­n trial centre where Lopera's patients receive an experimental drug to see if Alzheimer's can be averted. She chronicles the lives of people who care for sick parents, spouses, and siblings, all while struggling to keep their own dreams afloat. These Colombian families have donated hundreds of their loved ones' brains to science and subjected themselves to invasive testing to help uncover how Alzheimer's develops and whether it can be stopped. Findings from this unprecedented effort could hold the key to understanding and treating the disease, though it is unclear what, if anything, the families will receive in return. Smith's immersive storytelling brings this complex drama to life, inviting readers on a scientific journey that is as deeply moving as it is engrossing.