Guilty admission: although this book came out in early 2021, I didn't notice until late last year. (But when I noticed, I bought. In hardcover.)
It is a sequel to The Rise and Fall of D.O.D.O. , which was co-written by Neal Stephenson and Nicole Galland. And it's fortunate that I had (re)read that book just a few months ago, otherwise I would have been pretty much at sea here. Unless your memory is much better than mine, I suggest you brush up on the previous goings-on.
Ms. Galland is the sole author here. Which explains why the book flew under the radar for me; I "follow" Neal Stephenson on Amazon, but unfortunately failed to follow her. I've corrected that.
On to the plot: it's complicated, even for a tale involving witch-powered time travel. Our heroes have set out to combat their previous DOD employer, the Department of Diachronic Operations (DODO). Set up to make minor changes to the timeline to the USA's advantage, it has been subverted by an antagonistic Irish witch Gráinne, who is looking to bring back magic in the present era by undoing the triumph of science and technology. (The last nail in magic's coffin was the widely-circulated photo of the total solar eclipse of 1851.)
There's a lot going on, with heroic "rogue" ex-DODO operatives time-traveling to various key locales in order to undo Gráinne's schemes. An early disaster occurs in 1450 Japan, and it's essentially over before it starts. The main action takes place in 1606 London, where Gráinne is trying to get actual witch-spells inserted into the play Macbeth, replacing Shakespeare's original gobbledygook. There are also trips to 1397 Florence, saving an ancestor of … wait, that's kind of a spoiler. And also 309AD Sicily, where a lot rides on preserving a beautiful mosaic.
And there's a spectacular diachronic shear. You don't want to miss that.
There are some new female characters, like Robin Lyons. She's a hoot, totally different from her brother Tristan, a main character in the previous book. (He's offstage for most of this book.)
You don't need any supernatural powers to notice that things are being set up for at least one more book in this series. I'm in.