In July 1962, Edward Mayhew and Florence Ponting have just been married and are spending their honeymoon in a small hotel on the Dorset seashore, at Chesil Beach. The couple are very much in love despite being from drastically different backgrounds, with Mayhew the son of a schoolmaster and Ponting the musically gifted daughter of a wealthy industrialist and an Oxford philosophy lecturer.
During the course of an evening, both reflect upon their upbringing and the prospect of their futures. Edward is sexually motivated and though intelligent has a taste for rash behaviour, while Florence, bound by the social code of another era and perhaps having been sexually abused by her father, is terrified of sexual intimacy. Eventually this leads to an experience that will change their relationship irrevocably.