(Girls Waits With Gun, by Amy Stewart /Houghton Mifflin Harcourt)

Constance Kopp, the feisty heroine of Amy Stewart’s charming novel “Girl Waits With Gun,” sounds like the creation of a master crime writer. At nearly 6 feet tall, Constance is a formidable character who can pack heat, deliver a zinger and catch a criminal without missing a beat. Based on the little-known story of the real Constance Kopp, one of America’s first female deputy sheriffs, the novel is an entertaining and enlightening story of how far one woman will go to protect her family.

Like the real figure, Stewart’s fictional counterpart is drawn into her profession literally by accident. In 1914, Kopp and her sisters, Norma and Fleurette, were riding in their horse-drawn buggy on a New Jersey road when they were hit by a car driven by Henry Kaufman, a wealthy and pugnacious factory owner. Constance demanded that Kaufman pay $50 for damages. He not only refused but threatened the sisters with bodily harm and fired shots at their house. With the encouragement of the Hackensack, N.J., sheriff, Constance helped bring down Kaufman, a job that meant participating in a street-corner sting in which Kopp carried a revolver in her purse.

In “Girl Waits With Gun,” Stewart, author of “The Drunken Botanist” and “Wicked Bugs,” draws on little-known newspaper articles and other archival material — the title of the book is taken from a newspaper headline — embellishing the limited historical information by using her wily imagination. The result is a tale that’s as much the story of a woman who refuses to be bested by a bully as it is a chronicle of the social restrictions placed on women at that time. (Kopp herself had no interest in marriage and had wanted to be a lawyer or nurse but was dissuaded from these careers by her mother.)

Stewart’s descriptions of her characters, even the minor ones, are lively and delightful. The matron of a home for unwed mothers is “a short, squat woman with hair the color of a cast-iron pan and a disposition to match,” and a private detective wears “a black hat that a small child could have hidden inside.”

But it’s the usually prim Constance, suddenly unleashing her robust sensibilities, who steals the show. When the diminutive Kaufman threatens Fleurette, Constance throws him against a wall “hard enough that his skull cracked the plaster.” It’s a shocking moment that, as with many others in the book, Stewart imbues with humor. “If you’d like to pick a fight with a man your own size,” Kaufman says while Constance pins him to the wall, “I’ll send one over.”

A secret from Constance’s youth plays a key role in “Girl Waits With Gun,” as does a subplot surrounding a factory girl whose baby disappears. But mainly, this funny, well-plotted novel describes how one incredibly strong woman breaks the rules regarding ladylike behavior in the early 20th century.

When our statuesque heroine applies for a job as a store detective, the petite interviewer explains that the profession calls for someone unobtrusive. “You’re better suited for something more rough and tumble,” she tells Constance before showing her the door.

Stewart seems to be keeping the door open.At the novel’s end, the sheriff offers Constance a most unsuitable job for a woman. Even readers with limited powers of deduction can surmise that we haven’t heard the last of Constance — or her gun.

Carol Memmott frequently reviews books for The Washington Post.

On Saturday, Sept. 12, at 3:30 p.m., Amy Stewart will be at Politics & Prose, 5015 Connecticut Ave. NW., Washington, D.C.

On Sunday, Sept. 13, at 3 p.m., Amy Stewart will be at One More Page Books, 2200 N Westmoreland St., Arlington. Va.

girl waits with gun

By Amy Stewart

Houghton Mifflin Harcourt. 416 pp. $27