The pleasures of the second season (eight episodes) of “City on a Hill” are myriad. A scabby, garrulous, violent tale of Boston law and order in the 1990s, it juxtaposes a corrupt FBI agent (played in wonderful form by Kevin Bacon) and an aspirational black prosecutor (equally as well cast and acted, cementing Aldis Hodge’s reputation) amidst black gangs, project lives, and drug deals. Bustling subplots energize every scene. The settings are so, so gritty and the 90s music interjections so apposite. The ensemble cast is first-rate, standouts being Pernell Walker as a black community paragon and Jill Hennessy as a questing Catholic wife and mother. Dirty-realistic tales like this can readily founder, either ending up as noir porn or as sentimentalized journeys, but not City on a Hill: the serpentine storyline delights time and time again. Like all superior noir, few characters are pristine and some of them are shockingly malevolent, yet somehow every character is given the dignity of an arc that renders him or her human. The first two seasons have each felt complete and satisfying, leaving plenty of room for at least Season 3.