Okay, first off - this was, hands down, the best McDevitt I've read to date. If you've not read McDevitt, and are at all a fan of Science Fiction, you need to go out there and find yourself a copy of 'The Engines of God,' 'Infinity Beach,' 'Deepsix,' and 'Chindi.' Now. If you're not a huge fan of Science Fiction, let me tell you, though there's some astrophysics in there, McDevitt writes a lot more sociologically, adventure-action, and philosophically than nearly any other contemporary science fiction author I know, with the exception of Robert J. Sawyer. That said, his style is quite deft, as is Sawyer's, and a lot of people just don't 'get' it - as is obvious from some of the reviews written here. I happily suggest reading a chapter in the store prior to purchase, though I've yet to meet someone while working in my bookstore's Sci-Fi section who didn't like McDevitt.
Okay, fan-boy praising hereby endeth.
The story picks up the character of Priscilla Hutchins (who, now married and with a kiddy, plays a much more administrative and planet-bound role) and the storyline of the Omega clouds. Strange clouds that pop up, find anything remotely geometrical (especially, say, buildings), and blast them to bits. They're all over the universe, but why worry, as the one heading towards earth is not due for another, oh, nine hundred years. Yawn.
But one of them being tracked by the Academy makes a right turn, and this time, in McDevitt's nearly lifeless galaxy, seems to be setting its sights on levelling an alien race who are somewhere around the Ancient Greece level of evolution. In about nine months.
The race is on - but to do what? Try to stop the cloud - no one knows how. Try to save the race - again, how do you save a race that's about to be hit by tsunamis, tidal waves, tornadoes and all the other horrid things the Omega clouds do? Obviously, it would be wrong to step in, break protocol, and talk to the natives?
Right?
The story is very high paced, and as is always McDevitt's style, you never know who will make it to the end (he is not above killing off a character in a completely realistic fashion - by which I mean there's no hero capable of dodging all the bullets all the time), and his tendancy to through in a few philosophical characters absolutely shines in this book. McDevitt, as always, delivered a solid adventure worthy of any Sci-Fi buff's attention, but in a manner accessible to those who don't read Sci-Fi on a regular basis. Superb!