Jerry Spinelli first met Ellen Adams 15 years ago in his hometown of Norristown, Pennsylvania. She introduced herself and explained that she too had grown up in town, in fact, just about a mile from where they were standing, in the county jail. Her father had been the warden, so his family had lived in quarters right above the main entrance to the prison.

Over the ensuing years the two became friends, trading emails and Christmas cards and even the occasional visit. Spinelli didn’t give much thought to Adams’ unusual childhood. “Finally several years ago it hit me what had been sitting in my lap, what she had dropped in my lap,” he says, “and that is a story: a girl grows up in prison. Good grief. You didn’t have to be Shakespeare to see that.”

So Spinelli took the basic outlines of Adams’ biography, living in the prison and losing her mother, and crafted it into his own story: The Warden’s Daughter. The novel takes place in the summer of 1959, when Cammie “Cannonball” O’Reilly is about to turn 13. She’s in “that exquisitely delicate transition period between little kidhood and big kidhood,” Spinelli says, and she’s starting to realize what she’s missed out on. Struck by the unfairness of her situation, Cammie sets out to find herself a mother, no matter what it takes.

Beyond the basic premise, Cammie’s story shares little with Adams’. She loses her mother when just a baby (in an accident that, despite seeming outlandish, really happened, albeit to different Norristown kid) and moves into the prison at a much younger age than her nonfictional inspiration. Not even Adams’ adorable dog Trixie, a mutt so small she would ram in and out of the prisoners’ cells by squeezing between the bars, made the cut.

Spinelli did, however, rely on Adams to flesh out the details of prison life, especially the very different culture of the time. Like Cammie, Adams was allowed not just to talk to the female prisoners but even to go into the exercise yard with them. Today, such a degree of trust is almost unimaginable.

The larger setting is similarly nostalgia-inducing: the town may be called Two Mills, but it’s indistinguishable from Norristown. The streets Cammie roams are real, though they look different now. The shops Cammie visits have long since closed and the prison itself sits empty, an imposing reminder of a time gone by. “Most of these places are gone now,” Spinelli says, “but they really did exist then, and you can still find traces of the Norristown in the book, the Norristown of 1959.”

Despite his often sentimental perspective on the past, Spinelli doesn’t sugarcoat the difficult parts of Cammie’s experiences. She struggles to cope with the losses in her life, often taking her pain out on those around her or engaging in petty mischief. “In this day and age of entitlement and coddlement and participation trophies…I think there’s nothing bad about a little dose of reality,” Spinelli says. Bad things happen and our ways of coping, especially as children, aren’t always that healthy.

Nonetheless, Spinelli is wary of assigning a message to the book—he just hopes readers will be as compelled by the tale of a girl growing up in prison as he was. After all, he says, “what’s a higher calling than telling a good story?”

Alex Heimbach is a writer and editor in California.