The Bookseller and the Earl by Callie Hutton

Miss Addie Mallory is finished with the husband hunt. After six London Seasons as a wallflower, she convinces her parents that she should be allowed to use her dowry to buy a bookstore in Bath where she can live her life the way she wants.

Lord Grayson, Earl of Berkshire, has never gotten over his deceased wife’s betrayal with his own brother. He plans to make his life all about his son, Michael, who is deaf. When Grayson’s sister-in-law serves him with court papers declaring Michael incompetent with the intention of having her own son named as Grayson’s rightful heir, he turns to Addie, a dyslexic bookstore owner, for help.

Addie takes a personal interest in helping the boy. However, as time passes, Grayson and Addie’s joint venture to keep Michael from being declared incompetent leads to feelings and desires neither one of them expected.

Or necessarily wanted.