THE BOONDOCK SAINTS

In Boston, Irish American fraternal twin brothers Connor and Murphy MacManus attend Mass, where the priest mentions the fate of Kitty Genovese. Later, while Connor and Murphy are celebrating Saint Patrick's Day with friends, three Russian mobsters arrive and try to shut down the pub so they can demolish it for the valuable land underneath. Despite Connor and Murphy's attempt to talk them down, a brawl ensues, in which the Russians are defeated and humiliated. The next morning, when two of the Russians seek revenge, the brothers beat them to death in self-defense.

FBI Special Agent Paul Smecker is assigned to the case and finds that the police and the press see the MacManus twins as heroes. The duo turn themselves in at a police station, where Smecker interviews them. After the twins retell their incident to Smecker, he declines to press charges and allows them to spend the night in a holding cell to avoid attention from the media. That night, they receive a "calling" from God telling them to rid Boston of all evil.

Connor learns that a local hotel is hosting a meeting of the Russian mob. Having equipped themselves with weaponry from an underground gun dealer, the twins kill nine Russian mobsters, while Rocco, a friend of the twins and errand boy for local mafia boss Giuseppe "Papa Joe" Yakavetta, surprises them after being sent by his boss to carry out a hit. Realizing that he was set up, Rocco agrees to help Connor and Murphy. That night, they hunt down and kill Vincenzo Lapazzi, Papa Joe's underboss, at a peep show.

Falsely believing that Rocco is behind the murders, Papa Joe hires the legendary hitman "Il Duce" to deal with the problem. Rocco takes revenge on his former crew and convinces the twins to shoot up a gambling den so he can execute a criminal he was once forced to assist in a heinous crime. As they depart, the trio are ambushed by Il Duce. Although they manage to repel the attack, the three men suffer serious wounds, including the loss of Rocco's finger. The trio retreat to a safehouse where they cauterize their wounds.

Hours later, as the police secure the crime scene, the investigation seems futile since the twins covered their tracks by spraying any blood left behind with ammonia. However, Smecker happens upon Rocco's finger and analyzes it, eventually tracing the clues back to Rocco and his allies. This leaves Smecker in a difficult conundrum; he struggles with the choice of whether to prosecute the three men or join them in their cause as he believes they are doing the right thing. After getting drunk at a gay bar and subsequently taking advice from a reluctant priest, Smecker decides to help the trio.

Later, the twins and Rocco inform Smecker that they plan to assassinate Papa Joe at his mansion, but Smecker learns that they are walking into a trap. The twins are captured, and Rocco is shot and killed by Papa Joe. As Papa Joe leaves, Smecker arrives disguised as a prostitute and tries to rescue them before being knocked unconscious by Il Duce. While the twins say their family prayer over Rocco, Il Duce enters the room and prepares to open fire. However, he instead finishes the prayer – revealing he is the twins' father and deciding to join his sons in their mission.

Three months later, Papa Joe is on trial for the third time. However, the on-scene reporters anticipate his acquittal. The twins and Il Duce, aided by Smecker and a group of sympathetic Boston Police Department detectives, infiltrate the courthouse and take the spectators hostage. Unmasked, they make a speech stating that they intend to eradicate evil wherever they find it before reciting their family prayer and publicly executing Papa Joe. The media dubs the three as "the Saints".