It was the best of times, it was the — well, weirdest of times. If any novel showcases its author's inventiveness and creative fecundity in equal measure to her penchant for swan-diving right over the top into self-indulgence, Undertow is that novel. I loved this book almost exactly as much as I was frustrated by it. The story is set on the swampy colony planet Greene's World, where the requisite Evil Corporation exploits the natives in the interests of mining a precious substance called omelite, which exists nowhere else in the universe. This premise is not exactly poised to walk home with any Hugos for originality, to be sure. But it allows Bear to create her most vividly realized and marvelously textured setting to date. I'm so used to grungy, dimly-lit spaceships and rainy, Ridley Scottish urban hellholes, that to see a story set almost exclusively on boats and barges and boardwalks afloat on a watery world gets my attention.

Greene's World is way out in the Rim, among the most remote of colonized worlds, and far from the laws of Earth deep in the Core. So it would seem that open revolution is the only choice for those humans who wish to stop the exploitive and inhumane practices of the Rim Charter Trade Company toward the native intelligence, the amphibious ranid. But as we soon learn, opposition to the Rimmers goes even deeper than expected. André Deschênes is a hired killer for the Rimmers, but he wants out of the business. His goal is to learn the fine art of probability manipulation, as practiced by folks known as "conjurers." When Deschênes assassinates Lucienne Spivak, an agitator who has come into possession of information damaging to the Rim Corporation from sources unknown, he is suprised to find he gets his chance. Lucienne's conjurer lover, Jean Gris, decides, instead of the expected act of vengeance, to train Deschênes in the art of conjuring and bring him over to their side, as it were.

This whole "conjuring" business is where Undertow annoyed me more than anything. Sure, it's kind of a nifty idea, but as we soon see, Elizabeth Bear seems to be one of those writers who's interested in quantum physics mainly because so few people understand the first thing about it, and therefore it offers an opportunity to introduce good old indistinguishable-from-magic concepts into a story. The whole notion of manipulating luck and affecting probability is given the sketchiest of explanations at best. The closest we get is some vague explanation about how it's "a useful manipulation of the observer effect," in the words of Gris. "So you can change the world if you just think at it right." Sorry, but from a hard-SFnal standpoint, that smacks a little too much of new-agey, wishful-thinking twaddle like The Secret to me. "Just think at it right" isn't exactly the kind of language that would have impressed John Campbell. For all that it has any scientific application, Bear might as well have had Dumbledore pop up to wave his wand whenever someone needed out of a nasty scrape.

Still, I have to give Bear props for knowing how to keep the action racing along effectively enough that you don't ever really dwell on the story's weaknesses too much. Throughout, Bear displays a deft hand at clever surprises. Revelations about individual characters as well as secrets about the ranid and the origin of omelite show real creative inspiration, and the latter of these involves one of the more brilliant storytelling applications of the Many Worlds Hypothesis I've seen this side of Philip Pullman. All this quantum indeterminacy stuff also lets Bear throw out one of the most berserk climaxes it's ever been my wide-eyed amazement to read. She might not be very good all the time at getting these concepts to make literal sense in the context of her narrative. But there's no denying she knows her way around a memorably explosive setpiece.

Bear has never lacked for ambition. Undertow is in many ways the most ambitious novel of her career to date. Like a great many ambitious undertakings, its reach often exceeds its grasp. But that it has as much entertainment value as it does in spite of this is a tribute to its author's undeniable talents. Yes, for the most part, the story does make good sense — even, with some of the revelations Bear cooks up for the climax, giving us moments of brilliance — if you're willing to shrug and accept that its metaphysical musings (I don't think I've ever seen so many references to Schrödinger's Cat in one novel) are just serving the same narrative function that the more-honestly termed magic serves in fantasy. Taken as an adventure novel, with characters both human and alien engendering the necessary sympathy, and with moments of action that are truly off the chain at the best of times, Undertow can be enjoyed as one more offering from the prolific and dauntless Elizabeth Bear that is sure to pull you under.