Escaped prisoner triggers manhunt for trailblazing woman cop in turn-of-the-century Jersey

“I was New Jersey’s first lady deputy sheriff . . . [and] the summer of 1915 felt like a brave and bright new age.” To fans of Amy Stewart’s “Girl Waits With Gun,’’ it couldn’t be clearer that we’re back in turn-of-the-century Paterson, N.J., with the Kopp sisters — crime-fighting Constance, her grouchy carrier pigeon-obsessed older sister Norma, and dramatic teenager Fleurette. White it may feel like a bright new age to Constance, it’s still one in which a woman can be hired as a deputy sheriff but can’t vote. When a suspect remarks, “Say, I didn’t know they had lady detectives,” her boss answers for her: “It’s a new idea. I haven’t made up my mind about it myself.”

“Lady Cop Makes Trouble’’ is the second book in Stewart’s charming and illuminating mystery series loosely based on the real law enforcement career of the formerly forgotten trailblazer Constance Kopp. In “Girl Waits’’ we saw Constance, 35 years old and single, evolve from crime victim to crime fighter. She gained confidence in her capability for the job, but now she has to convince everyone else. When it’s suggested that Constance has become the department’s “mother hen,” she bristles but characteristically finds a way to make it work: “I hadn’t thought of myself as a mother hen, but then again, I’d seen a hen peck an errant chick so sharply that she drew blood, so perhaps [that] was right.”

Desperate to prove her worth, Constance earns the task of guarding a prisoner in the hospital — who promptly escapes during her watch. Mortified but fueled by a “bracing sense of purpose,” she spends the rest of the novel trying to regain the trust of her champion, Sheriff Heath, by recapturing the escapee.

Clues lead her across the river to New York City, which allows Stewart to display the fruits of her historical research on the period, from the “derelict old saloons alongside fishmongers, dental parlors, and Yiddish tailors offering to buy old trousers,” to the sunlight streaming through the “grand high windows” of the beloved old Pennsylvania Station (which was demolished in 1964). Stewart’s generous helpings of period detail occasionally distract from the story but who can complain about the appearance of minor characters such as the local Rutherford, N.J., doctor whose sign out front reads “W.C. Williams, M.D.” (as in the Rutherford poet and physician William Carlos Williams)?

Stewart balances all these elements — the details of real crimes, the social history of the era, and the tension a good detective story requires — by telling the story in Constance’s sensible and appealing voice. It’s the voice of a woman with resolute moral character and endearingly human foibles; a modern woman pushing against the strictures of her time. Constance has a talent for noticing tiny details that escape her male colleagues, a skill that makes her a good sleuth but also a compassionate observer of those around her. Entering a sitting room she notices that every scrap of fabric in it is decorated with intricate embroidery and to her this is a valuable clue: “I’d always felt that one could read a woman’s discontent in the amount of embroidery in her sitting room,” and her suspicion is soon confirmed.

Whether Constance is tackling a criminal “in what had to be the most undignified position a woman had ever been seen in on the streets of Brooklyn” or pouring punch in a theater lobby for Fleurette’s Christmas pageant, her days and nights come vividly to life. And although the real crimes are solved by the end of the novel, Stewart leaves the reader wondering about one mystery still developing unsolved: the relationship between Constance and her married boss, Heath. “There passed between us a feeling that no one can understand who hasn’t hunted and captured a criminal,” Constance says: “We’d done something together that few people ever do.” What else might they do in the future? Readers will just have to wait — impatiently, no doubt — for book No. 3.

LADY COP MAKES TROUBLE

By Amy Stewart

Houghton Mifflin Harcourt, 320 pp., $26