The Reef follows the fancies of George Darrow, a young diplomat en route from London to France, intent on proposing to the widowed Anna Leath. Unsettled by Anna's reticence, Darrow drifts into an affair with Sophy Viner, a charmingly naïve and impecunious young woman whose relations with Darrow and Anna's family threaten his prospects for success. The affair becomes the reef on which four lives are in danger of foundering: two of them innocent, and two of them burdened with experience and tinged with desperation.

A challenge to the moral climate of the day, this story of the drastic effects of a casual sexual betrayal offers a clear-eyed assessment of the possibilities and limitations of human love.