In September 1918, soldiers stationed near Boston suddenly began to die. Doctors found the victims' lungs filled with a strange blue fluid. They identified the cause as influenza, but it was unlike any strain ever seen, and medical science proved powerless against it. In desperation, people turned to folk remedies, while frantic officials closed all public places and everyone was required to wear masks. But the virus was unstoppable, relentless, devastatingly lethal. By the time the epidemic ran its course, over 600,000 people were dead, more than all U.S. combat deaths of the 20th century.
