The Duc de St. Quentin and his son arrive in Paris to support the would-be king, Henry. However, as in any court of intrigue, there are others that would thwart Henry's ascension. From assassination attempts to spies within the family servants, will the St. Quentin family survive the royal court? Or will they take actions into their own hands and assure Henry's ascension by force?
The New York Times made the following announcement on July 14, 1900,
"A young romantic novelist, Miss Bertha Runkle, of New York City, will make her debut in the August Issue of The Century Magazine with the first chapters of a novel which will run through eight numbers of the periodical. The work is described as a dramatic romance of love and adventure, and is entitled "The Helmet of Navarre." The scene of the tale is laid in Paris during the siege by Henry of Navarre, and the action occupies the four days preceding the Sunday when Henry entered the city to accept the Roman Catholic faith. Miss Runkle is the daughter of Mrs. L.G. Runkle, a woman well known in New York literary circles."