This all started with a war photographer named Seamus Murphy, who found me through a mutual friend. Would I be willing, Seamus asked by email, to lead a tour of Washington’s roughest neighborhoods for him and a woman he described as a “musician/poet”?

A few days later, Seamus and the woman climbed into my beat-up Mazda. Rumpled with a thatch of unruly gray hair, Seamus sat up front, chatting in an Irish lilt and snapping pictures as we passed tattered storefronts, littered lots and street corners populated by young black men.

The woman was in the back, quiet and inscrutable, gazing out the window and writing in a journal.

“How you doing?” I said, eyeing her in the rearview mirror.

Her hair was long and black, and she had deep-set, intelligent eyes. In a perfectly elegant British accent, she expressed gratitude for the tour. Every once in a while, she chuckled at something I said, then fell silent, her attention on the passing scenery, her pen moving across the page.

“Polly” was how Seamus referred to her.

They had enlisted me as their guide presumably because, as a Post reporter, I could show them the other Washington, “the darker side,” Seamus said, the poverty- and crime-ridden corridors far from the White House, the marble and the monuments. I know the terrain, having covered the District for more than a decade and spent many days roaming the city’s poor and working-class neighborhoods. (My own guides have included Marion Barry, the late former mayor, who spent a few hours driving me all over Southeast D.C.)

As for Seamus and Polly’s tour, the larger purpose was not altogether clear. Their project, Seamus had said, involved a mix of photography, poetry and songs rooted in the travails of three places: Kosovo, Afghanistan and Washington. “It’s awkwardly difficult to define,” Seamus had written in an email.

So off we went toward Anacostia, among Washington’s most violent neighborhoods. We drove past liquor stores and carryout joints along Good Hope Road and Martin Luther King Jr. Avenue. We passed the campus of St. Elizabeths Hospital, a mental institution where the Department of Homeland Security is relocating.

We went by the M.L.K. Deli, Matthews Memorial Baptist Church and the IHOP, which I told them was Southeast Washington’s only sit-down restaurant. Farther north, I drove through a housing project and pointed out a spot that was once home to a thriving methodone clinic.

Here was Benning Road, infamous for its shootings. Here was South Capitol Street, another strip marked by carnage, a corridor that led all the way to the U.S. Capitol. And here was East Capitol Street, where the city had replaced a notoriously violent housing project with mixed-income townhouses, created under a federal program known as Hope VI.

At Alabama Avenue and Naylor Road, I paused in front of the largely vacant Skyland Shopping Center.

“They’re gonna put a Walmart here,” I said.

In my mirror, I could see Polly scribbling in her journal.

PJ Harvey rides the Metro train in Washington, D.C., a couple years ago. (Seamus Murphy)
Wait a minute

At the end of the tour, after dropping off Seamus and Polly near their Adams Morgan hotel, I had an inkling that there was a bit more to this mysterious woman. Still behind the wheel, I Googled “Seamus Murphy” on my phone and saw that he had collaborated with a musician named PJ Harvey.

PJ as her legions of fans knew, was short for Polly Jean.

Unwittingly, I had chauffeured a critically acclaimed British rock star whose honors included not one but two Mercury Prizes, Britain’s best-album award, the last one for 2011’s “Let England Shake.”

I texted a musician friend about my encounter and asked whether he knew who she was.

“Female British rock/punk/blues singer 1994-present,” he responded. “Super cool.”

As a middle-aged man with three kids, a dog and a sizable mortgage, I’m more than willing to acknowledge that I am not what anyone would consider hip.

I still listen to the music I grew up with — the Stones, the Band, Talking Heads, Lou Reed and Dylan, whose “Blood on the Tracks” was what I played to help my son, Sammy, fall asleep when he was a baby. (His eyes routinely shut during “Idiot Wind.”)

I knew very little about new music, which I define as anything that has come out since, say, 1980.

The father of my daughter’s best friend is Brendan Canty, the drummer for Fugazi, the D.C. hardcore band I knew nothing about until I Googled it. Brendan smiled patiently when I confessed my ignorance. He laughed when I told him I had spent three hours in a car with PJ Harvey without having any clue who she was.

(Photo by Maria Mochnacz)
‘Pathway to death’

Twenty months after our drive, Seamus called again. He was returning to Washington and wanted another tour — the same tour — only this time he would be alone and he was bringing a video camera. He wanted to record my narration of our drive while he shot the scenery.

When I picked him up, he handed me a book of poems and photography titled “The Hollow of the Hand.” On the cover, he and PJ Harvey were listed as authors. He turned to the prose poem on Page 178, “Sight-Seeing, South of the Border,” the material for which Polly had gathered during our tour.

“Here’s the Hope Six Demolition Project, and here’s Benning Road, the well-known ‘pathway to death,’ ” the poem began. There were references to the IHOP I had shown them, and South Capitol, “zombies” and “baby-mamas.”

Polly had also turned the poem into “Community of Hope,” the first song on her new album, “The Hope Six Demolition Project,” scheduled for release next month.

Days later, after telling friends about my unknowing encounter with rock royalty, I decided it would be interesting to describe a musician’s artistic process. I wondered whether Polly would show me the journal she wrote in that day as I rambled on during our tour.

How cool it would be, I thought, to document how my words evolved into her art.

Her manager was enthusiastic about the idea when I first contacted him. Her publicists, too, expressed interest. I asked whether Polly would share her notes with me.

No, a rep later said, and she also wouldn’t give me an interview. But Polly “does love the idea of you writing about your experience that day.”

PJ Harvey sits along the Potomac River. (Seamus Murphy)
‘Community of hope’

The one thing PJ Harvey’s team was willing to share was the music video Polly and Seamus had made for “Community of Hope,” the song based on my tour. When I clicked on the link, the first image I saw was me in my sunglasses, as I appeared in the rearview mirror of my car.

Then I could hear the sound of my voice as I drove: “They took one of the old notorious housing projects and they leveled it and rebuilt it as mixed-income housing. It’s called Hope Six.”

Then the sound of a guitar, and images of a highway overpass, a train conductor’s view, a barber shaving an African American man. Then the sound of Harvey singing:

Here’s the Hope Six demolition project, stretching down to Benning Road

A well-known ‘pathway of death’

At least that’s what I’m told

With those words, I realized she had been paying close attention during our drive.

And here’s the one sit-down restaurant in Ward 7. Nice.

Okay, now this is just drug town, just zombies, but that’s just life

In the community of hope

The community of hope

The community of hope

The community of hope, hope, hope, hope

Now she switched to a different road and other places we had driven by.

Here’s the highway to death and destruction

South Capitol is its name

And the school just looks like a s---hole

Does that look like a nice place?

Here’s the old mental institution

Now the Homeland Security base

And here’s God’s Deliverance Center

A deli called M.L.K.

And the community of hope . . .

At this point, Seamus’s camera focuses on the landmark “Anacostia” sign at Martin Luther King Avenue and Good Hope Road. Then there’s the image of Union Temple Baptist Church. Inside the church, an African American man and three women are listening to a tinny iPhone rendition of Polly singing the phrase, “community of hope.”

The man leads the woman in harmonizing along with Polly’s voice, repeating the chorus several times until they reach the song’s final line: “They’re gonna put a Walmart here. They’re gonna put a Walmart here. They’re gonna put a Walmart here.”

Then, astonishingly, the camera cuts to a church choir standing in the pulpit, beneath an oversize rendering of a black Jesus, singing, “They’re gonna put a Walmart here.” PJ Harvey’s voice joins the chorus for a rousing finish that culminates with the image of chirping birds flying over the Anacostia River.

They’re gonna put a Walmart here

They’re gonna put a Walmart here

They’re gonna put a Walmart here

The video’s joyousness, punctuated by the image of a congregant raising his arms, is palpable. But then comes the uncomfortable thought: Salvation as a big-box store is hollow, especially for neighborhoods of boundless needs.

The community’s response to the song has not been especially welcoming. The leaders of Community of Hope, a District nonprofit, wrote Harvey a letter castigating her for an “incomplete” portrait. “Have you not trashed the place that, for better or worse, is home to people who are working to make it better, who take pride in their accomplishments?” the letter asked.

Then there was former mayor Vincent C. Gray, running for the Ward 7 council seat, who told the DCist website: “I will not dignify this inane composition with a response.”

Beyond the song, there is the reality that emerged nearly two years after I led Polly and Seamus on that tour.

Walmart reneged on its commitment to build two new stores in Washington, including the one slated for Skyland.

In fact, they would not be putting a Walmart here.