The Firemaster's Mistress is set against the rich backdrop of 1605 England. In the spring of that year, an explosion took place in London that was a harbinger of a far larger event: the Gunpowder Plot, in which a number of Catholics planned to blow up Parliament and King James I, and put a Catholic on the throne of England.

Francis Quoynt is a firemaster (someone who creates explosions) who is enlisted by Secretary of State William Cecil to spy for him. Quickly, Quoynt ingratiates himself among a number of men (including one who calls himself "Guido") who are deeply involved in the plan to kill the king. Francis's father, Boomer Quoynt, is a former firemaster who lives in what is now Brighton at the family home, Powder Mote.

Kate Peach is a glove maker and secret Catholic whose family perished during an outbreak of the plague in the summer of 1604. Her lover, Hugh Traylor, uses her for his own nefarious deeds, including hiding Catholic priests in Kate's home at a time when to do so is synonymous with treason. One of her other tasks is to find Francis Quoynt, who was once her lover but left her. Very soon the pair find themselves on opposite sides of the law: one to assist in the Gunpowder Plot, the other to stop it from going forward. Despite their past, however, Kate and Francis find themselves drawn inexorably towards one another once again.

Historical fact and fiction are seamlessly integrated in this lively, fast-paced novel (although it's over 500 pages long, this reader completed it in jut three days). The first twenty or so pages are a bit difficult to get through, but readers soon find themselves immersed in a world where treason and treachery are commonplace, and where each of the characters would do well to worry about who to trust. The reader has a hard time figuring out where to place loyalty and as a result gets emotionally involved with Kate and Francis's story, such as it exists in the first half of this novel.

The story abruptly (maybe too abruptly?) turns from romance to thriller a third of the way through; the ending of Kate's story comes from left field and feels tacked on. However, this is a well-researched, well-thought-out novel reminiscent of Philippa Gregory's novels, especially Earthly Joys. The author's interpretation (and, in some cases, fictionalization) of events is highly believable. Christie Dickason relied heavily on Antonia Fraser's The Gunpowder Plot to write The Firemaster's Mistress, reminding me that I should probably take my copy of that book down from my shelves and actually read it sometime.