When a late-summer hurricane slams into Boston, Detective Eddy Harkness and his Narco-Intel crew are thrown into the eye of a very different kind of storm. Dark Horse --- an especially pure and deadly brand of heroin --- has infiltrated the gritty Lower South End. Harkness soon finds that the drug is also at the center of an audacious land grab by the city’s corrupt new mayor and his shadowy power brokers. Meanwhile, Lower South End residents displaced by the storm use an obscure bylaw to move into Eddy’s hometown, and soon enough tensions are running high along Nagog’s tree-lined streets.

Eddy Harkness is a brilliant young detective who currently empties parking meters and struggles to redeem his disgraced family name. One night Harkness’s police-issue Glock disappears. Unable to report the theft, Harkness starts a secret search --- just as a string of fatal accidents lead him to uncover a new, dangerous smart drug, Third Rail. With only a plastic disc gun to protect him, Harkness begins a high-stakes investigation that leads him into the darkest corners of the city.