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 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.

Charlotte and Sidney find themselves at loggerheads but must work together in an attempt to rescue Miss Lambe. Tom tries to save Sanditon and his marriage, while Edward and Clara enter into a scandalous pact to finally get their hands on Lady Denham's inheritance.

As the Sanditon summer regatta approaches, Sidney wrestles with his feelings towards an old flame and Young Stringer reveals his feelings to Charlotte. With Lady Denham at death's door, the tensions between Edward, Clara and Esther finally come to a head - with surprising consequences.

On the night of the Midsummer Ball, romantic interests are finally resolved. However, the fate of Sanditon is in the balance when events conspire to leave Charlotte and the Parker family facing down impossible choices. Series finale.