When a young pregnant woman named Rosie Jones (Emilia Fox) boards a train, her enormous trunk starts leaking blood. Questioned by the police about the dead bodies inside, Rosie calmly reveals they are her unfaithful husband and his mistress. Convicted of manslaughter, she is imprisoned in a unit for the criminally insane due to diminished responsibility.Forty three years later, Walter Goodfellow (Rowan Atkinson), the village vicar of Little Wallop, is very busy writing the perfect sermon for a convention. He's completely oblivious to his family's problems: his wife Gloria's (Kristin Scott Thomas), unfulfilled emotional/sexual needs, starts an affair with her golf instructor Lance (Patrick Swayze), his teenage daughter Holly's (Tamsin Egerton) growing sex drive and physical maturity who constantly changes boyfriends; and his son Petey (Toby Parkes), a victim of bullying at school.New housekeeper, Grace Hawkins (Maggie Smith), becomes involved in their lives, learning about their problems: neighbor Mr. Brown's (James Booth) Jack Russell terrier, barks non-stop, preventing Gloria from sleeping; Petey has bullies; and Gloria has an affair with Lance (Lance calls Gloria, and Grace picks the phone and Lance talks to her without realizing that she isn't Gloria). Meanwhile Walter is nothing but sweet to Grace and makes her feel very welcome in his home. Walter is the object of ridicule for the entire village, since he is incompetent in every sense of the word. He is only tolerated due to his position as the vicar of the town. Even Lance approaches Walter and mocks him for the way the village makes fun of him, and yet Walter is only polite to Lance in return. ONe day, Gloria is spending time with Lance when she picks his phone and finds that he has been in touch with another girl, who Lance has been seeing on the side. Grace sets out to solve the problems in her own way by killing Clarence (the dog) as well as Mr. Brown (when Brown sees Grace trying to bury Clarence's body during a stormy night and Grance notices this), sabotaging the brakes on the bullies' bicycles which injures one of them and killing Lance with a flat iron outside the house for videotaping Holly undressing one night. Grace puts Holly on the path to recovery by getting her interested in cooking.As Walter prepares the sermon for the conference, Grace suggests adding humor (Like the joke about how God visited Earth 2000 yrs ago, met a nice Jewish girl and they are still talking about it). Also, seeing he has let his relationship slide due to his devotion to God, she shows him he can love his wife and God by looking at the erotic references in the Song of Solomon. As the problems in the household seem to gradually clear, Walter leaves for his convention. Gloria and Holly see Grace's photo on the news, showing her release and previous offenses, and they begin to realize what she's done (They find Lance's phone in Grace's large trunk in her room. She also shows the girls the video that Lance had been shooting of Holly secretly while she was undressing in her room). She's Gloria's long-lost mother Rosie Jones, who's come to meet her. After briefly processing the flood of information, Gloria asserts that when having a problem with someone, one cannot just kill them.Grace mentions this is the point she and her doctors could never agree on. Despite their disagreements, Gloria tries to help Grace with Lance's body, but cannot handle it. Over a cup of tea, the three women decide not to tell Walter or Petey any of what has happened.Nagging congregant Mrs. Parker (Liz Smith) visits to discuss the problem of the "church flower arranging committee". Grace, erroneously believing Mrs. Parker is about to turn them in for her crimes, attempts to hit her with a frying pan but Gloria stops her. Mrs. Parker, shocked, has a heart attack and dies. Walter returns from the convention just then and sees Mrs. Parker's body, but not realizing she is dead. Soon after, Grace leaves the family when order is seemingly restored among them.Walter then talks to Bob (Patrick Monckton) and Ted (Rowley Irlam), the waterworks employees, who say there is too much algae and the vicar's pond needs to be drained. Remembering Grace's victims' bodies are in the pond, Gloria, with a strained smile, offers them some tea. The film ends with an underwater shot depicting the bodies that had been placed in the pond, including the recently added Bob and Ted (implying that Gloria was the one who killed Bob and Ted and put their bodies inside the pond).