Currently you are able to watch "The Boondock Saints" streaming on Amazon Prime Video or for free with ads on Freevee. It is also possible to rent "The Boondock Saints" on Microsoft Store, Amazon Video, Apple TVonline and to download it on Microsoft Store, Amazon Video, Apple TV.
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.