Toronto author and former marine biologist Peter Watts is one of the foremost contemporary science fiction writers, a skilled craftsman with a visionary imagination firmly rooted in hard science. His first novel, Starfish, was a New York Times Notable Book. The novel’s sequel, Maelstrom, was equally compelling.

Watts’s new novel, Behemoth: Book One: B-Max, is the final book of his Rifters trilogy – or, as the subtitle indicates, half of that final book. As Watts explains in a somewhat (and justifiably) huffy author’s note, which will likely come as something of a surprise to readers outside the trade, “recent changes within the publishing industry” (ie, buying patterns at the American chain stores) forced him to divide his novel in two. Behemoth: Book Two: Seppuku is forthcoming.

Readers should not attempt to tackle Behemoth without first reading Starfish and Maelstrom. Behemoth begins five years after the events of the first two novels. In a corporate near-future, energy companies have sent long-term technicians (drawn from the ranks of the abused, the psychotic, and the violent, all credited with “pre-adaptation” to the stresses of isolation and undersea life) to tap the geothermal reserves of deep-sea rifts.

On the Juan de Fuca rift, this process releases an ancient microbe (which they call Behemoth) that has the power to destroy all life on the planet’s surface. The company sets off a nuclear explosion to destroy the microbe (and the infected rifters), but Lenie Clarke survives. On a mission of vengeance she spreads the microbe across the North American continent as the corporations quarantine, kill, and burn thousands in her wake to try to contain Behemoth.

As the third novel begins, a coterie of bureaucrats, scientists, industrialists, and their families have settled into a deep-sea haven, safe from both Behemoth and its survivors on the surface. They live in uneasy co-operation with the surviving rifters, who keep largely to themselves outside the station. When disease begins to befall the rifters, paranoia begins to rise and old wounds are reopened on both sides.

While it’s hard to pass judgement on what is really only half of a novel, Behemoth is something of a drop-off in quality from the first two volumes. There is an air of perfunctoriness to the storytelling, with a superficiality of characterization and rushed pace that is at odds with the slowly mounting paranoia of Starfish and the carefully modulated developments of Maelstrom.

Behemoth is still far superior to the bulk of contemporary science fiction writing, deftly balancing elements of thriller and military writing with post-apocalyptic visions and a fully realized world terrifyingly near our own. The trilogy is a must-read for even a passing science fiction fan.