This is an odd novel. It clearly sets out to be an explicitly religious novel, and it has a thumping great moral to it, as well as some rather miscellaneous parts.
Marcella and Henry lose their mother and are raised as Methodists. Marcella has a large fortune. They meet the Montague family. The sisters are unpleasant but the brother falls for Marcella. He attends a Methodist meeting and falls for her further, but is not religiously converted. Montague gets a clerical living from a relative despite his lack of religious commitment. He is jealous of Claudius Howard, a humble clergyman who is in love with Marcella but doesn't believe that he stands a change with her. Claudius resigns so as to get some distance from her, but this creates an emotional scene.
Marcella goes to Bristol for 2 month so Montague takes a curacy there and makes his move on her. She isn't convinced. Howard is in love with her, resigns his curacy and takes a missionary post in India. There's a long bit of Indian family history inserted for no very clear reason.
Henry is to marry Louisa Austin, Marcella is to marry Montague. There is quite a lot of social chitter-chatter and intrigue represented as their various circles learn of the matches, and make remarks on the Methodism of Marcella and Henry. Marcella becomes aware of how well ill-suited she is to Montague and how far apart they are in religious terms. She wants to break off her engagement. Marcella and Montague marry and set up house, but his father dies leaving no money so none of their house is paid for. Marcella is very busy with her various charitable works. She begins to regret her marriage, and that the family she has married into is concerned with ephemeral matters rather than serious concerns.
Montague is arrested for his debts. Marcella is told by a servant who heard via a letter from her brother. Marcella rushes to try to sort it out, but becomes very ill. Charles Howard arrives home and arranges for Montague's release. Marcella is very ill. They travel to Paris for her convalescence. Here Montague becomes very ill and dies; Marcella returns home. Eventually she marries Howard who is now quite rich, and all ends happily with everyone doing good work. There is an explicit strong moral about not marrying infidels and unbelievers.

Most of the characters are from the higher orders and so speak Standard English. Occasionally, however, they encounter characters from the lower orders (e.g. the lobster fisher and his family) in order to dispense moral advice, and these characters speak in a non-standard. There are also occasions where servants deliver plot points - as in the letter to Martha Jones, and the old gardener and again these characters are nonstandard.
Note that although there seems to be some specific placing (e.g. the Isle of Wight, Bristol, possibly even Wales) the nonstandard is very generic and includes both definite article reduction and 'bean't'.