A Reno singer witnesses a mob murder and the cops stash her in a nunnery to protect her from the mob's hitmen. The mother superior does not trust her, and takes steps to limit her influence on the other nuns. Eventually the singer rescues the failing choir and begins helping with community projects, which gets her an interview on TV—and identification by the mob.

Tired of the crime overrunning the streets of Boston, Irish Catholic twin brothers Conner and Murphy are inspired by their faith to cleanse their hometown of evil with their own brand of zealous vigilante justice. As they hunt down and kill one notorious gangster after another, they become controversial folk heroes in the community. But Paul Smecker, an eccentric FBI agent, is fast closing in on their blood-soaked trail.

Boston cop Pally is forced into early retirement, putting a strain on his marriage. Pally's stepbrother, Ray, attempts to lift his spirits by tipping him off to a sure-bet racehorse. But their attempts to secure the champion equine are thwarted by a local mob boss, who steals the horse as repayment for a gambling debt. With their investment on the line, Pally and Ray become entangled in a web of underworld crime and murder.