When a coach accident introduces Charlotte to the Parker family, she quickly seizes the opportunity to throw herself into the adventure she has craved all her life by returning with them to the developing seaside resort of Sanditon. Charlotte, however, soon discovers that the inhabitants of the town behave in curious and unpredictable ways that she could never have imagined.

Charlotte and Sidney clash again, only for Charlotte to be left confused by a chance encounter. Tensions surrounding Miss Lambe's arrival in Sanditon erupt at Lady Denham's grand pineapple luncheon, and Esther and Edward realise that Clara poses a significant threat to their ambitions.

Charlotte sets out to avoid Sidney, until a serious accident forces them together and to reappraise each other. When Tom brings a new doctor to the town, he and Lady Denham clash, while Clara makes a bold move in her bid to outplay Sir Edward and Esther.

The arrival of Miss Lambe's forbidden love causes Charlotte to question her opinion of Sidney. Clara witnesses a moment between Esther and Sir Edward that raises her suspicions about their relationship, with devastating consequences for Esther.

Tensions between Tom and his labourers erupt during the Sanditon cricket match. Charlotte and Sidney continue to clash, resulting in Miss Lambe being placed in terrible danger, while Lord Babington offers Esther a glimpse of a better future.