During World War I, scientists were trying to develop an antidote to the poisonous yellow cloud known as mustard gas. They discovered the gas was irrevocably damaging the bone marrow of affected soldiers. This gave the scientists an idea: cancer cells and bone marrow both replicate rapidly. Could mustard gas be used to fight cancer? Hyunsoo No details the discovery and development of chemotherapy. [Directed by Artrake Studio, narrated by Addison Anderson].