Onion John is set in the late 1950s in the quiet rural town of Serenity, near the Munkachunk Mountains and Musconetty Creek. This fictional community is patterned after Belvidere, New Jersey, a county seat near Krumgold's home with a population of about twenty-six hundred. This area, which was once settled by German Moravians, is near the edge of the Poconos Mountains.

A typical small town, Serenity boasts one hardware store, a drug store where boys congregate for ice cream, an amateur newspaper, an enthusiastic Little League baseball team, and an active Rotary Club. The surrounding land, while hilly and stony, supports flourishing orchards and gardens.

Onion John lives on the outskirts of town in a dilapidated house built of piled-up stones. This house has four bathtubs but no electricity or running water. The Serenity garbage dump, located next to the baseball diamond, is Onion John's source of food...