In 1844, Horace Wells, a Connecticut dentist, encountered nitrous oxide, or laughing gas, and began administering the gas as the first true anesthetic. His discovery would change the world, reshaping medicine and humanity’s relationship with pain. But that discovery would also thrust Wells into scandals that threatened his reputation, his family, and his sanity—hardships and triumphs that resonate in today’s struggles with what hurts us and what we take to stop the hurt.