Elena Ravalli was a seemingly healthy 37-year-old when she began to experience strange attacks of vertigo, numbness, temporary vision loss and crushing fatigue. They were classic signs of multiple sclerosis, a potentially debilitating neurological disease. It was 1995 and her husband, Paolo Zamboni, a professor of medicine at the University of Ferrara in Italy, set out to help. He was determined to solve the mystery of MS – an illness that strikes people in the prime of their lives but whose causes are unknown and whose effective treatments are few. What he learned in his medical detective work, scouring dusty...