Years ago, a neighbor told me an improbable story: When he was 9 years old, he and his 11-year-old brother drove a pony cart on their own for several hundred miles to attend the World’s Fair in Montreal.

It was the summer of 1967, and their journey from the suburbs of Boston to Expo 67 generated an outsize amount of press. Newspaper editors seemed eager to follow the hopeful story of the boys amid the troubling stories that dominated the front pages: civil unrest and escalating casualties in Vietnam. Over the course of their nearly monthlong trip, reporters detailed the progress of the brothers as they clip-clopped north at five miles per hour with King, their Shetland pony.

The national attention generated a flood of mail into the family home; some supportive, but much of it highly critical — accusing the parents of child neglect. Letter writers also expressed concern for the pony, King. A veterinarian was even called in, who deemed the pony healthy enough to continue the journey.

In the short documentary above, the “pony boys,” Tony and Jeff Whittemore, recount that as youngsters they were unaware of the controversial questions the trip raises. What constitutes responsible parenting? Did their parents do something dangerous, or was it a brilliant parenting move that taught lifelong lessons? What Jeff and Tony recall is a life-changing adventure made possible by a free-spirited mother who believed they could do it.