The romance concerns the love of Geraint, one of King Arthur's men, and the beautiful Enid. Geraint courts Enid. The couple marry and settle down together, but rumors spread that Geraint has gone soft. Upset about this, Enid cries to herself that she is not a true wife for keeping her husband from his chivalric duties, but Geraint misunderstands her comment to mean she has been unfaithful to him. He makes her join him on a long and dangerous trip and commands her not to speak to him. Enid disregards this command several times to warn her husband of danger. Several adventures follow that prove Enid's love and Geraint's fighting ability. The couple is happily reconciled in the end, and Geraint inherits his father's kingdom. Enid does not appear in Welsh sources outside of this romance, but Geraint was already a popular figure. Some scholars hold that the Erec from Chrétien's poem is based on Geraint, but others think the Welsh author simply replaced an unfamiliar French name with one his audience would recognize and associate with heroism.
The tale is analogous to Chrétien de Troyes' 12th-century poem Erec and Enid. Some scholars claim the two derive from a common source, while others believe Geraint is based on Erec or that Chrétien may have had a Celtic source. Alfred, Lord Tennyson based two of his Idylls of the King on Geraint and Enid. They were originally published as a single poem called "Enid" in 1859; he later split it into two poems: The Marriage of Geraint and Geraint and Enid (Tennyson).