The Helmet of Navarre by Bertha Runkle, Fiction, Historical

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?