Once again, Michael Harvey, who titled an earlier novel “The Chicago Way,” distills the City of the Big Shoulders into a dark-hearted, intoxicating, sometimes bitter beverage, as hearty as the Guinness poured at his pub, with a touch of that nasty stuff that Mithridates used to imbibe to make himself immune to poison.

Harvey starts with raw ingredients familiar to any Chicago lover or hater: a tyrannical mayor, venal lackeys, corrupt cops, L tracks, drug-dealing gangs with armed teens. In “We All Fall Down,” the secret ingredient is a pinch of biological weapon, all the more piquant because it may have been cooked up by the “good” guys.

Michael Kelly (so Chicago is that name), a former police detective turned private investigator, is summoned, with a touch of blackmail, by Homeland Security to provide protection for elite scientists investigating a possible release of weaponized anthrax.

Before long, Kelly’s been threatened by both armed gang members and rogue federales, while bodies that perished from a strange illness pile up in the morgue and hospitals. The discovery of a stash of body bags held by a ghetto profiteer indicates this isn’t accidental. When enough people have died, the feds and the city impose a quarantine that effectively isolates a large black neighborhood from more affluent white ones.

Harvey switches regularly between Kelly’s first-person point of view and a focus on other characters, notably Marcus Robinson, a 13-year-old gang soldier and natural killer. But even Robinson is no match for a mysterious white rifleman in a brown leather coat, wearing a mask, who may be the key to everything.

Harvey’s story is plenty thrilling, and the medical and quarantine elements nerve-jangling scary. But he and his creation are smart, too, and that intelligence lifts his novel even higher. Kelly’s hard-boiled cynicism, and his persistence despite that cynicism, echoes the Greco-Roman world as well as Dashiell Hammett’s mean streets. Harvey is a former student of classical languages: In a couple of spots in the novel, he taps Thucydides’ “History of the Peloponnesian War” as a touchstone. Not surprisingly, since this is a novel about plague, there’s a shout-out to Albert Camus, too.

In case the novel isn’t scary enough for you, Harvey helpfully lays out the real-life threat of a rogue biological attack in a back-of-the-book note.