Charity Royall is a young (late teens) woman who lives with her guardian in a small New England town. When Charity was a baby, Mr. Royall and his late wife rescued Charity from an extremely tenuous situation on The Mountain, where people live in abject poverty. Nonetheless, Mr. Royall now wants to marry Charity, a prospect that horrifies her because he is old, drinks to excess, and is generally repulsive to her. Despite Mr. Royall's having essentially raised Charity, they have little in common except a desire to live their lives on a bigger stage than that provided by North Dormer.
Charity works in the town library hoping to save money to fund her escape. One day, a New York architect, Lucius Harney, comes into the library looking for information about old houses in the area. Lucius stimulates an array of new fantasies for Charity--and, despite his greater education and higher social status, the two become lovers (the actual sex is scarcely hinted at) and, as one might expect from a Wharton book, Charity suffers some negative consequences as a result of violating the social norms of the era.
While many refer to Summer as Wharton's most erotic book, one must remember that that is a relative statement. Charity certainly experiences a sexual awakening, but the description of her relationship with Lucius is hardly titillating. I came late to Wharton's work and I admire her elegant prose, but Lily Bart, the complex and self-destructive heroine of House of Mirth, ruined me for a character like Charity, who is defined primarily by naivete and willful ignorance and self-deception.
For an instant the old impulse of flight swept through her; but it was only the lift of a broken wing.