Set in France around the turn of the seventeenth century, it is the story of a young woman named Constance who is in love with Gaspar, the son of her father's enemy.
Gaspar and King Henry IV, a friend of her father's, try to reassure Constance that it would be wrong to sacrifice her happiness, but she remains unsure.
Unable to make a decision about the marriage, she decides to spend a night sleeping on St. Catherine's Couch, a ledge of rock overlooking the Loire river.
Constance dreams about Gaspar's death in battle, and the agony she feels about the idea of losing him convinces her that marrying him is the right thing to do.
The tale may have been influenced by John Keats' poem "The Eve of St. Agnes", which is also the story of a young woman turning to a supernatural power for romantic advice.