As always, this volume is somewhat hard to summarize, especially for readers who might be unfamiliar with the plot and characters (if talking dodos, footnoterphones, cross-genre wars and Jurisfiction don't ring any bells, please see The Eyre Affair). I won't give you the plot, because you need to read it yourself. But I will note that the book is as full of biblio-punnery, allusions, name-dropping and imaginative ramblings as its predecessors, with the addition of much ebook angst added to the mix this time.
It's always a fun trip to dive into the BookWorld - just watch out for the eraserheads!
