As sad as I am that Jim C. Hines' Magic ex Libris series is ending, Revisionary is actually a fun ending to what's been a great series. This is not to say it's exploring new ground, but it does so in a fun and inventive way.
At the end of the last book, Unbound, Isaac Vainio revealed the existence of of magic, libriomancy, and the Porters to the world at large. We pick up, as should be expected, with congressional hearings.
Whole Isaac's real intention was to provide the good things to the world, like draughts of Lucy's healing cordial from The Lion, The Witch, and the Wardrobe to kids with terminal diseases, certain governments are much more interested in weaponry and military applications, as well as making sure magic isn't going to unbalance the current state of affairs.
Of course, the realization that magical creatures exist isn't helping things all that much either, since find out early on about Michigan's solution for taking out the vampire nest under Detroit in the abandoned salt mines. Which mainly involved sealing, collapsing, and setting fire to the nest.
Isaac and the Porters in the US have developed a compound outside Las Vegas in order to work on peaceful application of magic named New Millennium, all while being supervised by various government agencies.
Which is good for his niece, who's part of the clinical trials to get her amputated leg back.
The plot really gets rolling though, when four separate but simultaneous assassinations play out across the US, including the death of the Governor of Michigan by angry Werewolves. An organization of supernatural creatures appears to be behind the attacks, thus leading Isaac and Lena to chase down Vanguard with the help of former libriomancer now Renfield vampire Deb. This chase leads several different directions, including to off shore Atlantic area as the Coast Guard tries to get rid of a Siren colony.
We delve deeper into off the record detention facilities for non-humans, where any semblance of rights are suspended. We find out Vanguard's basic principle is one of getting non -human entities to safety via Underground Railroad style techniques.
(I'm glazing over quite a bit, including several supporting characters, but I really can't talk about them without hitting serious spoiler territory.)
As the threads of the conspiracy start unraveling and we finally get a good look at what's actually going on, the true ugliness of the plot comes across and we, like in a quite a few other stories, begin to wonder who the REAL monsters are.
As I said, I'm sorry to see such a fun series end, but it's not as though the author is planning on retiring any time in the near future, so....