‘Metropolis,’ set in Boston, centers around 6 characters and a storage facility

‘What happens when people who come from completely different backgrounds and places start to interact?’ That’s the idea behind B.A. Shapiro’s ninth novel, set in and around Boston.

David Wilson for The Boston Globe

It all began with an article in the Globe, said B.A. Shapiro. The historic Metropolitan Storage building in Cambridge was closing, and the story — and especially its evocative photos — sparked a hunch. Wouldn’t a place like that make the perfect setting for a novel with an ensemble cast?

“I had always wanted to write a book with characters who didn’t know each other, that were totally different, and brought together because of some kind of fluke of time or place,” said Shapiro. “And I saw that article and I thought: This is the perfect place for people from all walks of life to interact with each other.”

The result is “Metropolis” (Algonquin), Shapiro’s ninth novel, which features six wildly divergent main characters; all they share is their connection to the storage facility. “I just found the whole idea so intriguing: What happens when people who come from completely different backgrounds and places start to interact?” said Shapiro, who noted that this is her most sociological book (she holds a PhD in the subject). “In our society today that hardly ever happens. We’re all hanging out with people like us.”

Like many of her previous books, “Metropolis” is set in and around Boston. “I love Boston,” said Shapiro. “I’ve lived in seven or eight different places in and around the city. I came here to go to graduate school, and I never left.”

Despite her enviable authorial track record, including New York Times bestseller status, Shapiro said that the writing process remains grueling. “I love being a writer, and it’s what I wanted to be since I was a little girl, but it doesn’t come easily to me.”

“Metropolis” took 10 drafts. “I hate writing the first draft. That to me is incredibly painful. I love rewriting,” said Shapiro, who added that she’s currently in revisions on her next novel.

B.A. Shapiro will read at 7 p.m. Tuesday in person at Harvard Book Store.