Does humanity have a more implacable foe than time? There never seems to be enough of it, and when opportunities have passed, more often than not, they've passed. What wouldn't most of us give to go back in time and unmake our lives' worst mistakes? And what might we do differently now to change the world, if we only had the time?

A supremely confident and assured debut, The Seeds of Time established Key Kenyon as a top-flight space opera talespinner with a natural flair for the epic. Most inexperienced writers who attempt epic storytelling in their freshman effort end up with a heaping helping of epic fail, their talents not yet sufficiently honed to realize their ambitions. Kenyon slides into the pilot's seat of this adventure as if born to fly. It's certainly imperfect. Divided into two parts, the book's sprawling second half is less tight than its first. But what Kenyon has accomplished here is mostly very impressive, and you can see her taking her first forays into themes she'll explore again in later books.

The book juggles a number of ideas. It's an eco-disaster novel, from before Al Gore made environmentalism not merely a fad but a calling. For the hard-science mavens it explores the Many Worlds Hypothesis, in a concept Kenyon calls "cousin realities". And it's the story of its heroine's journey to personal redemption through learning how to let go of the past, a conceit made all the more poignant in that she makes her living routinely traveling back in time.

The novel's future is one in which the crossing of great interstellar distances has been achieved through a kind of time travel. Ships "dive" backwards in time from a fixed point in space, after traveling just far enough from Earth to avoid disastrous paradoxes like meeting themselves on the way home. They emerge where other worlds had once spun along their merry course in the galaxy's great rotation. Once they're done, they simply reverse the process and go home. These explorations are not only pragmatic but desperate. Earth's climate is shattered, and what may be humanity's final generations huddle fearfully in decaying cities while violence over dwindling resources breaks out everywhere. If an alien world can be found with flora that can be successfully imported to Earth, to kick-start the ecosystem in a last gasp for survival...

A few such worlds have been found, but nothing yet that can grow on Earth. Until the vessel flown by Dive pilot Clio Finn discovers Niang, a lush Eden with endless verdant forests. That the wildlife is a little strange isn't the half of it. Clio discovers a distressing fact about the world's greenery. It not only eats but replaces any metal it encounters with its own cellular structure. No seeds brought back from Niang will pass quarantine back on Earth. But if there's a chance it will grow back home, Clio decides, it must be worth smuggling in. Because Clio knows something the rest of her crew does not: Earth's days really are numbered. (I'll leave it to you to find out how she knows that.) But any plans Clio starts to form look like they may be quickly derailed by the leader of the landing party, who seems to be going barking mad...

This would be enough story for any one novel, let alone anybody's debut. But Kenyon just keeps adding dimension to it all, mostly through her complex development of Clio's character. This is a woman with, to put it mildly, a checkered past. The only reason she's still able to Dive — and she's gone well past the point when most Dive pilots have burnt out — is that she's a full-on drug addict, and whether she likes it or not, while it keeps her Diving, it's affecting her performance in other areas and drawing the unwanted attention of the law.

Every action Clio takes as the story unfolds is motivated by an urgent drive to wipe the slate clean, both for herself, those she loves, and the planet she calls home. The past may not go away if you save the future, but it gives you a much better motive to survive. A goal ahead, rather than a goad from behind. More than once, Clio is taken to the brink of despair — indeed, well beyond it at one point. Kenyon is not afraid to hurt her characters, so that their ultimate triumphs are all the more uplifting.

The ambitious plot (now there's an understatement) doesn't entirely avoid falling back on the obvious. We know, once Clio has left Niang with unfinished business dangling, that she'll be back soon enough. And the climax borders on the mystical. I'd also liked to have known more about the Earth's brink-of-disaster society. Precisely how and why did such an institution as the fascistic vice squad DSDE get so powerful?

But considering this is a first novel, it's remarkable how much Kenyon gets right. Supporting characters achieve impressive individuality, so that the tension between Clio and both her friends as well as enemies is always taut and compelling. Clio would let go of the past if she knew how. But there have always been so many people in her life holding her back — the DSDE goons who want to nail her for past crimes, plus her need to locate and care for her missing autistic brother — that, like the drugs that have kept her hanging on in the one career she's suited for, Clio's past has just kept her running in place. (This inner crisis of Clio's has a metaphor in the nature of time diving itself, in which ships travel temporally, but from a fixed position.)

Kenyon would revisit environmental themes two years later in Rift, and the notion of alternate universes would emerge again in her magisterial tetralogy The Entire and the Rose. That series would also feature a protagonist, like Clio, frantic to reconnect with a broken family. With such expansive SF sagas to her credit — rooted in carefully tuned plotting, good scientific speculation, and rich and sympathetic attention to character — it's surprising more people aren't aware of Kay Kenyon. If you're a lover of nuts-and-bolts space opera with a real human heart and soul, and you're frustrated that it's getting harder to find on bookstore racks overrun with boilerplate urban fantasy, the novels of Kay Kenyon are like an abundant, rich, green oasis in a barren and desolate post-apocalyptic wasteland.