At its height, the sale of enslaved people in Richmond totaled the equivalent of $440 million annually in today’s dollars. In the mid-1800s, Richmond was America’s second-largest hub for the domestic slave trade, with much of the city’s economy entangled in “the peculiar institution.”

Shockoe Bottom was filled with businesses – jails, auction houses, hotels, cobblers, tailors, blacksmiths – that all catered to the slavery trade. To announce a sale, businesses hung little red flags outside their doorways to inform prospective buyers.

And of all Richmond’s enslavers, Robert Lumpkin was the most notorious. Not only was Lumpkin the largest slave trader in Richmond, but he was so infamous for his cruelty, publicly beating and torturing those who attempted to escape, that his jail was known as “the Devil’s half acre.”

But the most curious element of Lumpkin’s life was his partnership with Mary Lumpkin, an enslaved woman who, it was said, acted as his “wife.” Purchased by Robert Lumpkin as a young girl and forced to have his children starting around the age of 13, Mary Lumpkin saw to it that her children were educated and found a pathway to freedom. After Robert’s death in 1866, Mary inherited his property and land; because of her, Lumpkin’s Jail was converted into a school that eventually became Virginia Union University, one of America’s oldest Historically Black Colleges and Universities.

Mary Lumpkin is the focus of Kristen Green’s new book “The Devil’s Half Acre,” a history that aims to illuminate the life of a woman that little is known about. Coming off the success of her first book, The New York Times bestseller “Something Must Be Done About Prince Edward County,” Green’s ambitious new work is sweeping in its scope, explaining what slavery meant to Richmond and Mary Lumpkin at both the macro and micro level.

Where her previous book combined investigative reporting and her own family’s narrative to explore Prince Edward’s shuttering of its public schools after Brown v. Board, rather than desegregate them, Green again turned to her journalistic toolbox to bring Mary Lumpkin to life.

Green first learned of Mary Lumpkin in 2011 while on an assignment for the Richmond Times-Dispatch. Black activists were demanding to reclaim Richmond’s African Burial Ground, a sacred space that was covered with pavement and used as a parking lot by Virginia Commonwealth University at the time. Three years earlier, an archeological dig had discovered the remains of Lumpkin’s Jail nearby.

When Green was assigned the story, she knew little of the domestic slave trade and of Richmond’s role in it. After conducting some research, she couldn’t get Mary Lumpkin out of her head.

“I just remember thinking, what does that mean to act as someone’s wife?” she says. “I knew that she couldn’t have consented. She wasn’t truly a wife. I was just interested, and it stuck with me after I finished the Prince Edward book.”

Realizing that the only enslaved woman she’d ever heard about as a child was Harriet Tubman, Green decided it was important to focus her next work on telling the story of another enslaved woman. While all histories involve some sleuthing, Green had her work cut out for her as much of Mary’s life remains unknown. By researching enslaved women with similar backgrounds and histories, Green triangulated their experiences to better understand Mary.

Green says she was partly inspired to pursue this line of detective work by historian Tiya Miles’ “All That She Carried: The Journey of Ashley’s Sack,” a National Book Award winner about women and slavery framed around a cotton sack that dates back to the mid-19th century. In her book, Miles confronts what she calls “the conundrum of the archives” — that written records usually favor those with the means to document their lives, and skew towards those with power. By mixing traditional archival facts with conjectures about other enslaved women’s lives, Miles attempts to understand her subjects.

“We had to become more comfortable with the spaces left in her narrative,” says Green, who spent seven years researching and writing her new book. “People are doing this work where they want to tell the stories of people who were intentionally erased and are using what we know more broadly about enslaved people and enslaved women to help expand the narrative.”

There’s plenty of macro history that will be eye-opening to most Richmonders. For instance, slavery was once Virginia’s most profitable industry; in the 1840s, Virginia was responsible for shipping nearly half of all enslaved people across state lines.

We also learn that Robert Lumpkin is something like an evil Forrest Gump, emmeshed in some of the biggest stories of his day dealing with slavery. Before he owned Lumpkin’s Jail, he was a plaintiff in the case of the Creole, a transport ship that seized by the 128 enslaved people held in its brig in 1841. The Creole was steered to Nassau where slavery had been abolished; 41 of those freed had been enslaved by Lumpkin.

Lumpkin also had a role in the fate of Anthony Burns, an enslaved Virginia man who captivated the nation after he escaped to Boston. Arrested under the Fugitive Slave Act of 1850 and tried in court, Burns was sent to Richmond, where Lumpkin made sure Burns paid for embarrassing the South. Burns was imprisoned and tortured for four months before he was put up for sale. He eventually was purchased by a Massachusetts pastor in 1855 and freed from slavery, dying seven years later from complications of injuries he sustained at Lumpkin’s Jail.

In the last chapter of her book, Green connects the past to today, including the recent removal of Confederate statuary from Monument Avenue and the various efforts to create a slavery museum in Virginia. She asks if Richmond will ever bring its hidden history to light.

“I hope that Richmond residents come to understand what a key role the city played in the domestic slave trade and how much it profited from the slave trade,” Green says. “I would love for Richmond to be known for telling that truth. We could go from being the city that told these false stories with Confederate statues to being the city that tells a truthful history with a slavery museum.”

And if Richmond ever does shine a light on this history it’s tried so hard to hide, Green asks if it will tell the story of Mary Lumpkin.

“The story of Mary Lumpkin is one story that is representative of enslaved people that were passed through Richmond,” she says. “She represents so much. Self-determination, survival, resilience and then certainly joy. She was able to get her children safe well before most enslaved people became free.”

The book launch for “The Devil’s Half Acre” will be held on April 12 from 5:30-7:30 p.m. at The Len, 15 N. 17th St., 23219. Free tickets can be reserved at fountainbookstore.com/green041222.