For generations, Alzheimer's disease has been treated as a tragedy that unfolds entirely within the brain — a slow interior collapse. New research from Washington University in St. Louis now suggests the brain may be less the origin of its own destruction than the destination: immune cells activated in the lymph nodes of the neck appear to travel inward and drive the neurodegeneration long associated with protein accumulation alone. If this model endures, it reframes not only how we understand the disease, but where — and how — we might intervene.