The familiar residents of Barchester take little part in proceedings, since most of the narrative revolves round the three families of Gresham, Thorne and Scatcherd.
Thorne knew that Mrs Scatcherd had been left high and dry by her husband's imprisonment and readily adopted the role of nurse to young Frank.
Dr Thorne feels he has to inform Frank Gresham, in strictest confidence, of Mary's background to allow him to decide if there may be an objection to her associating with his family.
However, unknown to nearly everyone, Mary's maternal uncle, Roger Scatcherd, has risen from humble beginnings to great wealth.
As young adults, Mary and Frank Gresham – the only son and heir of the squire of Greshamsbury – fall in love.
However, his parents need him to marry wealth; the squire has squandered much money on expensive and fruitless campaigns for a seat in Parliament and is grieved that he can leave little to his son.
As Mary is penniless and of suspect birth, such a marriage is inconceivable to his mother and to her relatives, the aristocratic de Courcys.
After consulting with lawyers, Doctor Thorne confirms that his niece Mary is the heiress, now wealthier than even Miss Dunstable.
Unaware of these developments, the still resolute Frank finally persuades his doting father to consent to his marriage to Mary.