Hard to explain this one ... Holt doesn't do easy plots. It's, as usual, simultaneously very funny and very serious. All about the physics and possibilities of multiverses, the nonlinear nature of time, doughnuts of many (surprising) kinds, and mathematics that don't necessarily add up the way ours do. This last has cropped up before in Holt's novels, starting in the J.W. Wells series, in various forms with different maths for different plots (such as achieving immortality by having somebody who calculates in base-8 instead of base-10 doing your accounts ... trust me, it actually makes sense ***GRIN***). The concept isn't always expressed as maths either ... sometimes it's just the abilities of somebody who's slightly out of sync with the universe they happen to be in ... atomically vibrating to a different drummer as it were. A part of me wonders if this is all leading to some higher, connects-everything plot although at the same time I can't see Holt having anything so obvious as a storytelling goal. He doesn't write obvious. Ever.
Ah well ... right now he's back on the waiting-impatiently-for-the-next-book list. :-)
Edited to add: And how could I have forgotten to mention the wonderful titles of some of the five sections of the book? Like "In the Beginning was the Misprint" and "One Empty San Miguel Bottle to Bring Them All and in the Darkness Bind Them"