In 1976, there's an outbreak of a disease that no one has seen before. All what they know is that resembles a disease that existed at around 1871, and that a Dr. Henderson was able to save most of his patients but the Chicago Fire destroyed his records. Dr. Earnshaw the doctor looking for a cure was approached by a man, Jeffrey Adams, who believes that he could help him. It seems that a Dr. Amos Cummings has prefected the art of time travel, and the plan is for Earnshaw and Adams to go back to 1871 and learn how Henderson cured his patients. But a glitch in the machines computers sends them the day before the fire not four days as intended.