On May 21, 1796, a young African-American woman slipped out the door of her owner’s mansion in Philadelphia and made her way to a ship that would carry her to then-distant New Hampshire—not to freedom, exactly, since slavery was still legal there, but far enough away that she might eventually be forgotten by the master.

Ona Judge had lived all of her 22 years in slavery, a condition that millions of African-descended Americans suffered. But the household from which she fled was different from all others. It was the nation’s first executive mansion, and her owner was its first president, George Washington.

Ona had come with the new president northward from Mount Vernon, living first in New York and then in Philadelphia. Settling there, President Washington circumvented Pennsylvania law, which required that enslaved persons be set free within six months of residing in the new state, by sending Ona back to Virginia from time to time, as if she were a different person each time she returned to his service in Philadelphia. Seeing that it was possible to live freely, Ona Judge finally took her chances when it was announced that she was being given as a gift to the president’s granddaughter. And now Washington reacted with furious efficiency, setting hired slave hunters to work and taking out advertisements in newspapers to gather information about sightings of the runaway.

It was in a library not far away from the first executive mansion that, more than two centuries later, historian Erica Armstrong Dunbar came upon one of those advertisements. She thought about what she read there, wondering about the young woman whom the newspaper called “Oney.” Then she began to dig deep. “I had a challenge,” Dunbar says. “Here was the president searching for someone he regarded as property—a person who would obviously take pains to hide herself. How could I find her? And why hadn’t anyone else found her and told her story?”

The result was a decade’s worth of combing through documents, tracing Ona’s path northward, a story Dunbar recounts in her new book, Never Caught. What she found along the way is a story that illustrates, once more, just how deeply slavery is bound up in our nation’s history. “I study the history of African-American women in early America,” Dunbar says. “I’m not a specialist in the life of George Washington as such.” But Ona’s story necessarily involves that hallowed historical figure. “For an enslaved person, Ona had a relatively good life in Washington’s household,” says Dunbar, “but the emphasis is on relatively. She was still his property, legally, and he worked hard to find her and get her back.”

That he did is testimonial to how invested Washington himself was in the institution of slavery, and if he regarded it as an evil, he also regarded it as a necessary one. Washington, first among equals, the most exalted of the founders, lived only a few years beyond Ona’s escape. His slaves were freed soon after his death. For her part, Ona lived until 1848, more than half a century after slipping away from the president’s mansion. She lived long enough to see the rise of a powerful abolitionist movement that would soon change the course of the nation’s history, but quietly, studying the Bible that she had diligently taught herself to read.

Ona Judge’s saga reflects poorly on our first president and on a young nation that, all these years later, is still struggling with race and racial injustice. Dunbar’s careful historical detective work also honors a woman hitherto lost to history, giving her a place in a much larger narrative. A slender book, Never Caught tells an outsize story—and one sure to make news.

Gregory McNamee is a contributing editor.