Quick-witted and energetic, Cianci was a political star in ascent, an “ethnic” who gave the Wonder Bread Republicans of the 1970s some cover to feign diversity. He demonstrated his considerable potential with a well-received speech during the 1976 Republican National Convention.

But the man could have taught a Brown University master class in self-destruction. He undid himself with his megalomania, bullying management style and alliances with the city’s more sinister forces. When he was forced to resign after his felony conviction in 1984 — for that assault in his home — Providence fairly sighed in relief.

But Cianci lingered in the city’s consciousness for several years as the bilious host of an afternoon radio talk show. Then, in 1990, he stunned everyone by running again for mayor — and winning. His slogan: “ He never stopped caring about Providence .”

It’s true that the presumably rehabilitated Cianci improved the look and feel of downtown Providence, and his unwavering support of the local arts scene helped to keep Trinity Rep open. Mr. Brant said that he was initially drawn to the Cianci project “by the idea of doing a profile of someone who once sat in this theater — who kept the lights on in so many ways.”

But it’s also true that Cianci’s perverse understanding of public service led to yet more corruption, culminating in a second criminal conviction, for racketeering, in 2002. He served several years in federal prison, then resumed his role as acid-tongued radio personality, eviscerating anyone who had dared to succeed him.

In other words: He never stopped.

“The Prince of Providence” maintains a parochial coziness, reflected in the inside jokes that win knowing laughs: the time that monkeys escaped from the zoo to take their own walking tours of the city (true); the stale Oreos that Cianci lackeys ate while he committed that infamous assault (true); the assortment of Cianci toupees, including an “action rug” for use at crime scenes and in inclement weather (true.)