In the late 1800s, a new disease arrived in North America from Europe and began to claim the lives of children everywhere. Though most today have never even heard of this illness, it would routinely kill over ten thousand children in a single year—more than polio might take in an entire decade. After much trial and tribulation, a shot was developed that helped both those already afflicted with the illness, and those who might one day become infected. But the shot was dangerous, and many parents refused it for their children.

In 1932, a safer version of the shot was developed, but contained a new ingredient never before tried on humans. Due to aggressive immunization campaigns, children all over the country began to receive this shot. Within a year, a new mental disorder—unknown to even the most knowledgeable child psychologists in the country—began to appear. It affected toddlers, and mostly boys. Children were losing the ability to speak and would take little interest in any other humans—even their parents.

The Autism Vaccine chronicles the story of two of these children—one known throughout the world, the other completely unknown until recently—and why modern medicine’s attempts to explain what happened to them have so far come up short.