Omega by Jack McDevitt. Somewhere in early March, we picked up a copy of Locus's "Recommended Reading" issue, which featured quite a few reviews talking about the "rebirth of space opera" and that sort of thing. Which got me thinking that I really wanted to read some really large scale science fiction, so a bookstore run was made, and a stack of books was brought home.
A number of reviewers said very nice things about this book, which turns out to be the latest volume in a loosely connected series begun with The Engines of God (about which more later). It probably would've been a good idea to read some of the other books before reading this, but it's actually written in such a way that it's not a big problem.
The concept is just fantastic stuff: In 2230 or thereabouts, humanity has expanded out into the Galaxy, but failed to find any other advanced civilizations. Remnants of such civilizations have been turned up, though, and they show an oddly cyclical pattern of utter catastrophe every 8000 years or so. This is eventually traced to waves of "omega clouds," strange cloud-like objects that sweep through the galaxy in waves, attacking and destroying technological civilizations (somewhat indirectly-- they home in on and attack structures containing right angles).
The operation of the clouds is completely mysterious-- nobody knows how they hold together, let alone how they locate their targets-- but there's no real sense of urgency about the question, as the cloud that's headed toward Earth won't arrive for another thousand years or so. But then, a routine survey of an unexplored star system turns up something that changes everything: a thriving pre-industrial civilization, sitting directly in the path of an omega cloud. Suddenly, a way needs to be found to stop the cloud, and fast.
This is sort of a cross between a Space Opera and a Big Dumb Object story. The clouds are basically BDO's, but the scramble to save the "Goompahs" (as the aliens are christened, based on a resemblance to some beloved cartoon characters) has some of the "plucky band of adventurers thwart an alien menace" feel of good Space Opera. Whatever it is, it's great fun. There are nifty alien societies, cool technical gizmos, wonderful cosmic mysteries, and the resolution of the whole omega question is about as good as you'll find for SF on this scale. The plot throws enough twists to keep you on your toes, and none of them feel cheap.
I wouldn't call this Great Literature-- the writing is unexceptional, and the characters a little flat-- but it's a good, fun book in the fine tradition of large-scale SF. It's like Rendezvous With Rama, only with a plot, or Brin's Uplift Trilogy, only with a halfway sensible conclusion. I definitely recommend it, and plan to go back to read the earlier volumes (and, in fact, have finished The Engines of God, though there are several books ahead of it in the booklog queue).