Reared in slavery, beaten by her masters, struck in the head as a young woman with a heavy weight that caused narcoleptic spells — the story of Harriet Tubman is well-known. This petite, illiterate woman ran away to the free North, and then repeatedly returned to her home ground of Maryland, spiriting away not only her own family, but dozens — perhaps even hundreds — of slaves, never once getting caught or losing anyone in her charge.

When the Civil War broke out, Tubman became a nurse and intelligence agent. Her exploits are well documented, including the dramatic liberation of nearly 800 slaves in South Carolina in a Union army expedition Tubman planned and led — the only time a woman, let alone an ex-slave, managed such a feat.

No wonder, then, that Tubman is a staple of children’s stories, not to mention three recent biographies. Scrupulous scholars have detailed what Tubman did, but they have all been stymied when having to account for how she did it. Although Tubman obliged countless journalists and biographers with stories about her adventures, she rarely divulged her methods. A woman who could have run the Central Intelligence Agency, she never gave up the secrets of her trade.

Enter Beverly Lowry, a novelist, who has “imagined” her subject’s life in her new biography, “Harriet Tubman” (Doubleday, 432 pages, $26). Reviewers have already expressed a certain uneasiness about Ms. Lowry’s methods. She sometimes resorts to the nugatory “must have been,” but usually she is bolder and more effective than biographers who try to bootleg factoids into their narratives — those statements that sound certain, but are actually bootless speculation.

Ms. Lowry reminds me of Faulkner’s Ike McCaslin in “Go Down, Moses,” who scrutinizes his family’s commissary books and ledgers to recreate the past and make it live again. Like Faulkner, Ms. Lowry even uses italics to denote words taken from documents she has studied while envisioning life as Tubman lived it day-to-day. The author often shifts tenses, moving from past to present, back to past again, simulating the kind of dynamic that occurs when attempting to make a continuum of history.

If Ms. Lowry’s method succeeds, it is because she is a historiographer who examines what other biographers have done with the Tubman material and explains how she regards their redactions of Tubman’s words. Through Ms. Lowry’s text we see how the historical record develops and what it omits.

By all accounts, Tubman was a devout woman who believed her successes were the result of divine will. She spoke in parables. She believed God talked to her, and whites and blacks called her Moses. But Tubman’s words require parsing, since like many ex-slaves, she was schooled to use coded language that occluded her life, preventing her masters from understanding her deepest feelings.

Ms. Lowry focuses, for example, on Tubman’s earliest recorded memory. Harriet is in a tree cradle when “the young ladies in the big house where my mother worked came down, caught me up in the air before I could walk.” Ms. Lowry dwells on these words, wondering about the circumstances of the tree cradle story. Unable to supply any more details, and she concludes:

See her: a special child with a large spirit, irresistible to the young white women. Her small, compact body in flight, airborne, like a ball pitched to the sky, the baby who would one day find her own way to fly. Arms out, she catches at the air, aloft.

Most biographers would be afraid to write this way: It seems too fanciful. But biography, Ms. Lowry knows, is about more than facts — so long as the biographer never forgets what facts are available. Biography is about imagining a life, wondering why as a young women Tubman hired herself out, became a “freelancer,” as Ms. Lowry calls her in an inspired choice of words. Tubman refused to be a house slave, preferring the hard manual labor that put her in the fields with men.

“Harriet Tubman” is a biography that goes to the core of character, using the record to create a fully imagined life. Here is Tubman making her first escape: “From among the laborers, most of whom are men and boys, a young girl — compact, tightly wound, her low center of gravity a certain sign of surefooted speed — sets off at a quick clip.” There is no document that justifies this sentence, but look at Tubman’s photographs and consider the whole life. Ms. Lowry’s prose, you will find, runs right along with her subject.

crollyson@nysun.com