Warning: wikipedia contains spoilers
The plot concerns the Dale family, who live at the "Small House" of the title. The house is a Dower house, ie a house built to serve as the dwelling of the widowed mother (Dowager) of the owner of an estate. The estate owner, in this instance, is the bachelor Squire of Allington, Christopher Dale. Dale's mother having died, he has allocated the Small House, rent free, to his widowed sister in law and her daughters Bell (Isabella) and Lily Dale.
Lily has for a long time been unsuccessfully wooed by John Eames, an junior clerk at the Income Tax Office, while Bell is in love with the local doctor, James Crofts. The handsome and personable Adolphus Crosbie is introduced into the circle by the squire's nephew, Bernard Dale. Adolphus proposes to Lily, who accepts him; but he almost immediately deserts her in favour of Lady Alexandrina de Courcy, whose family is in a position to further his career. Lily accepts her misfortune with patience, and remains single, continuing to reject John Eames as a husband, though retaining his faithful friendship. As with all Trollope's novels, there are many strands to the plot, and numerous minor characters. Plantagenet Palliser (of the "Pallisers" series) makes his first appearance in some scenes as he conducts a dalliance with Griselda Grantly, daughter of the Archdeacon introduced earlier in the Barsetshire Chronicles.