I sat on my Bainbridge Street deck with the pepper scent of pear tree blossoms and a clattering of starlings and doves and robins reading Beth Kephart's new young adult novel Dr. Radway's Sarsaparilla Resolvent, due out next month from New City Community Press /Temple University Press. Across the street, a construction crew was finishing a contemporary twin with pewter colored brick and ipe cladding. Their norteño love songs drifted on over; one of the crew had the habit of shouting lines before they were sung, like a scorned man trying to make a point.

The city was full on me, William Quinn, the 14 year old protagonist of Dr. Radway, might have said, in the perfectly clipped cadence of Kephart's imagined 1871 Philadelphia. Kephart's writing is indeed alive to the material world; readers of her Sunday Inquirer columns share in her wonder at this city's post-industrial hurtle. But cast in the late 19th century, her potent streets crackle and slur. Here is William on Broad Street, buckling up courage to avenge the killing of his older brother Francis by the policeman Socrates Kernon. He's seeking a woman named Pearl—his hook to snag Kernon—and here she arrives.

Finally, from behind, on Broad, William hears a hackney cab squeal to a sudden stop. He hears the quick snap of a brusque shout, the crash of overskirts and lace, the nasty slap of whip crack, and then, just as fast, the horse pulls off, tipping onto its back hooves and up before the driver has it back in its charge. The speed of its escape pounds hard into the street. A terrible rumple is left in the road, a mangle of person and skirts.

Kephart has explored the territory of sibling loss before, in the 2010 novel Dangerous Neighbors, which takes place during the Centennial world's fair in Fairmount Park five years after William's journey to set things straight in Dr. Radway. (William appears in Dangerous Neighbors and Anna and Katherine, twins torn apart by a skating accident in that book, beg at the shadows of Dr. Radway, as Kephart puts it, "in that funny place between dream and knowing.")

Throughout the new book, which is strikingly illustrated by Kephart's husband William Sullit, the rather good-hearted William imagines conversations with his lost brother, a street smart hustler who had won their mother's heart. Ultimately, William will have to prove to himself and their mother he's every bit the protector his brother was. But William is no conniver. He's forced to negotiate the gray murk of morality as much as the smog and mud of the industrial city (much of the book takes around the Baldwin Locomotive Works below Spring Garden Street). William wades in it, sometimes chest deep. "What good is honesty if the truth is helpless?" he wonders.

And so does the reader, for this book, despite its strong narrative pull, leaves the reader feeling as open-ended as William is uncertain.

"We still seen what we seen," [William's aspirational best friend] Career says, tired now, his vest gone ragged.

"We did."

"We seen what's possible."

"Possible for them," [says William].

"Possible for anybody."

Or is it? Kephart is interrogating the 19th century, as much as she's celebrating it (in the book's afterword, she calls it, quite accurately, "spectacular"). Industry's destruction is everywhere here, as it was in her masterful 2007 book Flow, a feminist portrayal of the Schuylkill River. "How is it," she asks in the voice of the river, in Flow, "that something man has made is more spectacular than all that he will never fashion with his own hands? Birds, for instance. Clouds. The eternity of rivers."

Industry hammers on in William's path, pressing people sometimes into compromise and deceit. "The sound of the machines comes down around him," Kephart writes in Dr. Radway,

the lathing and whining and huffing and steaming of the manufactories of old Bush Hill. It's a bee-in-the-ear sound—the infernal song of warp split and hank twist, beam and grist, the raking in of steaming coal, the mash and heat of pig iron. Corner to corner, at every careen and cross, it's here: the Iron Works, the Tool Works, the Car-Wheel Works, the plundering shake of the Pennsylvania Railroad, the stones being knocked from the trench.

One of Kephart's gifts in her ongoing written exploration of Philadelphia is the capacity, and the willingness, to look on all that's here with honesty, to allow for confusion and contradiction, for might and violence all at once. A writer does so by loving her characters, even the rotten ones, even the city so sour it might burn. And by bathing it, as only this one can, in fullness of breath.