Every century has its inconvenient truth, clearly stated, that nobody important wants to receive. In this episode, Risto follows four people who said something true, gave the evidence, and were ignored for a long time anyway: Nikander of Colophon, who identified lead poisoning two centuries before Christ; James Lind, who proved how to cure scurvy in 1747 and watched the Royal Navy take half a century to listen; Ignaz Semmelweis, who reduced maternal mortality by ninety percent and died in an asylum, of the very disease he had been trying to prevent; and Clair Patterson, who measured the lead in our bones and was attacked by the industry that had put it there.