As evident from his book’s subtitle, “Theodore Roosevelt’s Doomed Quest to Clean Up Sin-Loving New York,” Richard Zacks has a pleasingly colorful writing style. Luckily it is a style that mirrors, especially at the outset of this little-known and somewhat dappled adventure, the brashness of its central historical figure, Theodore Roosevelt.

In the early 1890s, a few short years before the city of Brooklyn joined with New York to become what we now know as the five boroughs of metropolitan New York City, a political and moral reform movement arose in the city, especially among well-heeled (and largely Republican) civic leaders. The city then had a population of roughly two million people, among them 30,000 prostitutes. To summarize in a blander manner than the lively Mr. Zacks: A series of investigations revealed that prostitution had links to police corruption, which in turn had links to Tammany Hall, the largely immigrant, working-class political machine that controlled New York City. The result was that in 1894, voters threw the bums out and installed a reform mayor, who appointed 36-year-old Teddy Roosevelt president of a four-man, bipartisan-at-least-in-name police commission to clean things up.

The ambitious Roosevelt, who had been wasting away in a Washington, D.C., civil service post, leapt at the chance. At first his vigorous efforts and his widely reported nighttime rambles in the city’s rollicking, vice-ridden neighborhoods were very popular. But then Roosevelt decided the police should enforce the laws against selling alcohol on Sundays. Roosevelt’s ethical (and valid) point was that allowing police to selectively enforce or ignore the alcohol ban led to favoritism and corruption.

The problem was, Sunday was the only day off for working people, and enforcement deprived them of a customary form of entertainment—socializing in the city’s saloons. Meanwhile the law did not prohibit sales of alcohol in hotels and the clubs of wealthy gentlemen. Class warfare? Tammany Democrats thought so, and they used Roosevelt’s efforts to thoroughly whip the city’s Republicans in the next election. For the remaining years of his term, Roosevelt was mired in grinding conflict with fellow commissioners and undermined by upstate Republican politicians who distanced themselves from him in order to maintain their own political power. He finally sought escape in a political patronage job in Washington.

Theodore Roosevelt’s term as police commissioner was, as Zacks entertainingly points out in his layered and well-researched Island of Vice, a significant learning experience for the future president. And probably also for residents of New York City, who never gave their native son a majority of their votes.