Author Kate Clifford Larson does not have any axes to grind in The Assassin’s Accomplice: Mary Surratt and the Plot to Kill Abraham Lincoln, the story of the first woman hanged by the U.S. government. Larson makes no claims to correcting the record or offering new evidence about Lincoln’s assassination. Instead, she simply relates the largely overlooked story of the woman who ran the Washington, D.C., boardinghouse that became the locus of the Lincoln conspirators. “Surratt was no innocent bystander who, as some sympathizers would claim, was duped into complicity by her co-conspirator son, John, or the wily and handsome young actor John Wilkes Booth,” she writes. If Larson is not completely successful in the telling, it is because so many details of Surratt’s story still remain clouded in obscurity, obliging her to sprinkle the text liberally with qualifiers such as “perhaps,” “may have,” and “remains unknown.”

Born Mary Elizabeth Jenkins in 1823 in Prince George’s County, Maryland, Surratt lived much of her life in quiet desperation. She lost her father at age two, then later broke from her mother by rejecting Episcopalianism and becoming a Catholic, a somewhat radical step at the time. At 16, she married John Surratt, the father of an illegitimate child with another woman. The couple opened a tavern in Surrattsville in southern Maryland, across the Potomac River from Virginia. His heavy drinking and gambling forced her to shoulder business and family responsibilities.

Following the outbreak of the Civil War, Surrattsville became a hotbed of secessionist sentiment, and its proximity to Virginia made it ideal for illicit cross-border activities. Mary’s oldest son, John Jr., became a courier for the Confederacy, frequently traveling south to Richmond and north to Canada with messages and instructions for underground operatives. “The likelihood that any of this activity went on without Mary’s knowledge—indeed, tacit approval—seems impossible,” Larson writes.

After her husband died in 1862, Surratt rented the tavern and moved into a house on H Street in Washington, which she operated as a boardinghouse. John Wilkes Booth frequently visited, creating “a fluster among the house’s female inmates,” noted boarder Louis Weichmann. While Booth usually called on Surratt’s son John, he often carried on long private conversations with her. Other Lincoln conspirators, including George Atzerodt, David Herold, and Lewis Payne, visited, as well.

On April 14, 1865, foiled in his plot to kidnap Lincoln, Booth killed the president instead, while Payne viciously attacked Secretary of State William Seward. The trail quickly led investigators to the Surratt boardinghouse, where police arrested Payne, who was still wearing a shirt stained with Seward’s blood. Surratt’s connection to Booth soon became clear: she had conducted a private conversation with Booth that afternoon, delivered a package for him to Surrattsville, and made sure that guns hidden at the tavern would be available that night. In the ensuing military trial the combination of damning evidence and an inept defense all but guaranteed a guilty verdict. Even though five of the trial’s 12 commmisioners recommended leniency,