Came a Cavalier is the story of Constance Galt, a beautiful girl who has great qualities of loyalty and loving-kindness, but whose outlook has been limited by a legacy of poverty and intolerance and whose faith in mankind has been shattered by an unhappy love affair. Service in France, as a "searcher" for the American Red Cross, at the end of World War I, broadens her horizons immeasurably, and a young and extremely engaging doctor, Duncan Craig, brings a new element of romance into her life. But it is with the coming of a cavalier—Tristan de Fremond, a French cavalry officer of irresistible attractions, belonging to the famous Cadre Noir at Saumur—that her existence is completely transformed.