[In this adaptation of the original, the setting of the film is moved from London to Saucier, Mississippi, home of a riverboat casino. Actual filming, however, took place in Natchez, due to the real Saucier being situated in Harrison County and not bordering the Mississippi River.]
In a quiet, beautiful community Mrs. Marva Munson, an elderly, God-fearing widow lives. She answers the door one sunny morning to find the charming Professor Goldthwaite H. Dorr, a pretentious Southern dandy, darkening her doorstep. He explains who he is and expresses his interest in Mrs. Munson's spare bedroom, which she has advertised to let. He explains that he is a musician and asks if it would be all right for him to use her basement as a place for recitals with his fellow "musicians". She accepts the terms and agrees. Mr. Dorr's fellow "musicians" are actually a gang of criminals, consisting of:
-Lump, the incredibly dumb but tough football player. -The General, a quiet tough-as-nails donut cook with expertise in tunneling and garroting troublesome individuals. -Garth Pancake, a mustached animal trainer for TV commercials with expertise in explosives. -Gawain, their "inside man", a young janitor who works on the "Bandit Queen", a riverboat casino.
With all of their talents combined, the group of criminals plan to dig a tunnel from Mrs. Munson's basement to the casinos' underground counting room. To avoid Mrs. Munson's hearing the digging, they play orchestral CDs as to seem that they are rehearsing, so she will not get suspicious. They dispose of all the unused dirt in Hefty trash bags.
After a series of comical mishaps that threaten to derail their plan, which include Gawain getting fired from the casino and Garth blowing his finger off in an accidental explosion (while demonstrating the 'safety' of C4 to the others), they break through the wall of the vault and snatch the loot, a scheme made even easier by Gawain, who has been rehired at the casino and is able to quickly repair the puncture in the wall. Mr. Pancake is able to rig a small explosion that will collapse the tunnel so it will never be discovered. The explosive seemingly turns out to be a dud, so Pancake ventures down the tunnel and, after examining it, inadvertently re-activates its timer. With about ten seconds before the tunnel collapses, Pancake crawls with all haste to escape, but his Irritable Bowel Syndrome (IBS) starts to act up and this slows him down. It suddenly explodes and he is shot out of the collapsing tunnel and smashes into a table which has the money on it. Upon hearing the rumble, Mrs. Munson walks downstairs and finds out what her tenants have done. Outraged, she tells Dorr in a private conversation to either return the money to the casino and go to church to repent their sins, or else she will call the police. Dorr tells her he will consult the group. Not willing to give up the money, the gang decides to murder her and draw straws to do so.
Gawain loses, and must therefore shoot Mrs. Munson. When he goes to shoot her, he has a flashback of himself at ten years old, coming home with a spaniel puppy in his arms and asking his alcoholic, couch potato of a mother if he can keep it. She refuses and slaps him, claiming "you wait 'til your daddy gets home, he gonna lay into you proppa!" Upon hearing him murmuring "please momma, I love you. He won't shit in the house, I'll train 'im up proppa and wipe his butt an' everything", Mrs. Munson (whom Gawain was visualizing as his mother) demands to know what he is doing with her pillow, and snatches it away. After receiving a slapping, Gawain informs his fellow comrades he can't shoot her. An outraged Pancake tells him to accept his responsibilities and shoot her or face the prospect of being a coward, to which the group concurs. During an argument and brawl with Pancake, Gawain accidentally shoots himself in the chest and dies.
Lump and the General dangle the trash bag with Gawain's body over a bridge and drop it when a huge garbage barge heading out to the garbage island passes below them. Meanwhile, Pancake steals the money and attempts to escape with his girlfriend, Mountain Girl. However, Dorr is no fool, and checks to confirm the money is still present. Dorr sends The General chasing after them, who promptly kills them both with his patented strangling wire, and their bodies are then dumped on the barge.
This time, the General pulls the short straw and walks up to Munson's bedroom with his wire strangler, planning to strangle her in her sleep. He also back-flips his cigarette into his mouth so that the pungent fragrance of tobacco doesn't wake Mrs. Munson. As he is about to kill her, he is surprised by an alarm clock sounding and accidentally swallows his lit cigarette. He reaches for a glass of water on the nightstand to get a drink, only to realize this is where Mrs. Munson kept her denture. In disgust, he retreats, and still choking, he staggers backwards into the stairwell, trips over the cat, and falls down the stairs, smashing his head against the wall and cracking his skull, dead on impact.
When Dorr and Lump dispose of the General on the bridge, Lump suggests to Dorr that they give the money back to the casino. Dorr insists that he is stupid and tells him that he has to do the killing. Lump refuses and tries to shoot Dorr instead because he doesn't "want to harm a nice old lady". The gun doesn't fire, so Lump peeks down the barrel while pulling the trigger. It turns out that Dorr deliberately left the chamber under the hammer empty, and Lump tests the revolver to see if it works. He shoots himself in the face and falls over the bridge rail onto the garbage barge passing under the bridge, timed perfectly due to Dorr's ability to anticipate Lump's every thought and move.
Dorr, left standing, sees a raven sitting on a statue of death, which reminds him of Edgar Allan Poe's poem "The Raven". Being a great admirer of Poe, he pauses to reflect. When the raven flies off, the head of the statue breaks and falls off, whacking Dorr on the head. Dorr too, falls over the bridge, but his coat catches on the bridge's underside railings, thus hanging him. His coat soon tears and he falls onto another garbage barge.
Mrs. Munson wakes up, ignorant of last night's proceedings. She sees a crack in the wall where the General's head impacted, though she can't figure out how it got there. She then goes down to the basement to discover that the gang has apparently disappeared, leaving all the money behind. She decides to return the money, but when she shares her story with the sheriff, they think she has gone batty, refuse to believe her story. To humor her, they tell her to keep the money, and agree that she can give it to the "bible school" in South Carolina, Bob Jones University. In the film's last moments, Pickles, the cat, is seen scurrying across the bridge and poking his head over the side with Pancake's finger in his mouth. He then drops it onto the passing garbage barge, disposing of the last remaining piece of the villains.