How might rare medical conditions be a force for good? This probing documentary reveals the extraordinary people who are helping international scientists make medical breakthroughs. A woman who can smell Parkinson’s disease helps doctors find a new way to diagnose this debilitating condition. A pioneering stem cell trial provides hope for those with multiple sclerosis and a patient’s inability to sense pain inspires a new generation of pain relief. The World’s Most Extraordinary People meets the scientists and patients at the heart of these stories – and takes us right to the edge of scientific understanding.