The opening assignment in Amy Stewart’s new novel, “Lady Cop Makes Trouble,” seems straightforward. The year is 1915 and a prisoner being treated at Hackensack Hospital in New Jersey has escaped during a thunderstorm that plunged the facility into darkness. A sheriff’s deputy is ordered to recapture the prisoner — an elderly German con man named Herman Albert von Matthesius, who has been arrested for posing as the director of a sanitarium and going so far as to drug and marry one wealthy young woman while she was under his care.

"Lady Cop Makes Trouble" by Amy Stewart (HMH)

Nothing, however, is routine about that sheriff deputy’s assignment, starting with the identity of that deputy. Constance Kopp is Bergen County, New Jersey’s first female sheriff’s deputy. A sturdy professional, Constance can pound the pavement and tackle fleeing ruffians, as well as — if not better than — any man. But, as readers of Stewart’s first Kopp Sisters novel, “Girl Waits With Gun,” know, the most remarkable thing about Deputy Constance Kopp is that she is inspired by a real person of the same name.

New Jersey had only recently passed a law allowing women to serve as deputy sheriffs, matrons, and police officers when the real-life Constance Kopp was hired in 1915 as a deputy by Bergen County Sheriff Robert Heath. Kopp’s exploits — which included firing a handgun and chasing down male criminals and slapping handcuffs on them — were breathlessly described in newspapers of the time. Stewart drew on those accounts for “Girl Waits With Gun,” which fleshed out some of Constance’s actual adventures, as well as imagining her off-duty life with her two real-life sisters — Norma and Fleurette.

Mysteries featuring 19th and early-20th century professional female detectives — whether based on real women or completely fictionalized ones — have been around for almost as long as their male counterparts. Kathleen Gregory Klein, in her landmark critical work, “The Woman Detective,” identifies a “Mrs. Gladden,” who appeared in an 1864 British novel called “The Female Detective,” as the first of her kind to appear in print. But, whatever their value as feminist texts, the characteristic flaw of many of these tales of lady detectives in petticoats is that they suffer from a surfeit of quaintness.

Stewart’s “Kopp Sisters” series is sometimes guilty of being a bit twee. (There’s a running subplot, for instance, involving the sublimated romantic feelings between the fictional Constance and her married boss), Stewart offsets the series’ sentimentality, however, with her dogged attention to the specific — and often sordid — details of Constance’s work life, which include treating prisoners with “petroleum oil” and “delousing powder.” Here is Constance at the beginning of “Lady Cop Makes Trouble,” summarizing her most recent exploits as sheriff’s deputy:

“I’d served divorce papers to an estranged wife, investigated a charge of illegal cohabitation, chased down a girl attempting to run away on a train, put clothes on a prostitute who was found naked and from opium in a card room above a tailor’s shop . . . The prostitute had soiled herself and had to be washed in the card room’s dingy basin, and the girl running for the train bit my arm when I caught her, and still I assert that I had never been more content. Improbable as it may sound, I had, at last, found work that suited me.”

As the novel unfolds, that job is threatened. The wily von Matthesius escaped while Constance was on duty outside his room at Hackensack Hospital. If he isn’t tracked down quickly, not only will Constance be booted off the force, but, in accordance with laws then in place, her beloved boss will not only lose his job but also take von Matthesius’s place in jail.

The author Amy Stewart (Terrence McNally)

Stewart starkly dramatizes what the loss of Constance’s paycheck would do. As the steady wage earner among her sisters, Constance keeps food on the table and underwrites Fleurette’s dubious career as an actress. Throughout the novel, Constance confronts nightmare images of female dependency: a young girl who answers an ad for “housekeeper” and is pressured to perform other services; an Italian immigrant prisoner who would rather stay in jail than be returned to her life with her abusive husband. Thanks to Stewart’s historical research, “Lady Cop Makes Trouble” is also filled with vivid images of turn-of-the-century New Jersey towns and Manhattan landmarks — such as the cavernous waiting room in the original Penn Station, and Murray’s, an opulent Times Square restaurant tricked out as a Roman temple, complete with “a barge fit for an emperor floating in a grand fountain.”

“Lady Cop Makes Trouble” takes readers on a lively chase through a lost world. It’s a colorful and inventive adventure tale that also contains a serious message at its core about the importance of meaningful work to women’s identities and, in some cases, survival.

Maureen Corrigan, who teaches literature at Georgetown University, is the book critic for the NPR program Fresh Air.

Lady cop makes trouble
A Kopp Sisters Novel
Houghton Mifflin Harcourt. 310 pp. $26