"Tiamat's Wrath" by James S. A. Corey

Finally, some alien action. Books 5, 6, and 7 were dull and uneventful, focused on humans that might as well have been set in the 20th century. I'm unsure if it was worth pushing through books 5 through 7 to get to this preamble to book 9, but we'll see.

I do have many issues with the book 8, though. They took the most exciting character and froze him for the whole book. Fortunately, this is fixed at the beginning of book 9. There were only two most important events in "Tiamat's Wrath:" when "underground" attacks and exploring alien artifacts. Oh, and they blew up a system. Also, what happened to Amos was intriguing.

This is a precursor to book 9, setting up the pieces for the primary battle between humanity and whatever the hell is "on the third side of the gates." I'm happy that soon I'll be over with the Expanse series, primarily because of the books 5 through 7.