[ What’s the creepiest reading experience N.K. Jemisin ever had? ]

If Jemisin has a weakness, however, it’s a propensity for didacticism. “The Ones Who Stay and Fight,” which she describes as “pastiche of and reaction to [Ursula] Le Guin’s ‘The Ones Who Walk Away From Omelas,’” takes an already preachy story as its springboard — let no one pretend that the genre isn’t soapbox-prone — to argue with both the past master and the rabble of reactionaries who have harried efforts to diversify science fiction. It posits a sort of utopia while firing salvos at offstage skeptics (“It’s almost as if you feel threatened by the very idea of equality. Almost as if some part of you needs to be angry”). The result makes for a lifeless exercise from a writer known for her ferocious and sorrowful vitality. Inexplicably, this piece opens the book, and it would be a shame if browsers unfamiliar with Jemisin’s work were to conclude that it is representative of the whole collection.

It isn’t, although it does sometimes seem that Jemisin worries overmuch about getting her message across. One of her fortes, as she notes herself in her introduction, is “playing with genii locorum … places with minds of their own.” Two of the stories in this collection depict young men — poor, dark-skinned and overlooked — who embody their cities, New York and New Orleans. The near-perfect “Sinners, Saints, Dragons, and Haints, in the City Beneath the Still Waters” recounts how Tookie, left behind because he wouldn’t fit in the family car, and an elderly neighbor cope during Hurricane Katrina, aided occasionally by a wisecracking, bat-winged “lizard.” Their antagonist is a big, dark thing moving beneath the floodwaters. The events of the story itself make the nature of this thing quite clear, yet Jemisin feels obliged to double down on its allegorical nature by having Tookie label it “the Hate” and the “lizard” explain “this thing make people so ugly they don’ even want to help each other.” This unnecessary exposition kills the shiver of the sublime in a story otherwise marked by honed descriptions, winning characters and captivating New Orleanian dialogue.

There is, fortunately, much more to love in this collection. Some of the stories are good old-fashioned science-fiction yarns shot from new angles, like “Walking Awake,” a response to Robert A. Heinlein’s “The Puppet Masters,” in which a middle-aged caregiver raising human children whose bodies will eventually be taken over by parasitical aliens experiences a moment of revolutionary awakening. “The Trojan Girl,” a fleet-footed cyberpunk thriller, conjures a gang of digital entities, artificial intelligences gone rogue, roaming a virtual universe and seeking access to a greater reality. “Valedictorian,” a follow-up set in the same world but much later, after the AIs have merged with some of humanity, features one of the determined, defiant girls that often turn up in Jemisin’s work, then flips her view of her society upside down. Any fan of the Broken Earth novels will eagerly seize upon “Stone Hunger,” set in that series’ universe, in which another fierce girl, an “orogene” with the power to stoke or subdue geological tensions, pursues the man who destroyed her city.

The nameless heroine of “Stone Hunger” encounters a “stone eater” (a type of being Jemisin invented for the Broken Earth series), a living statue, human in shape and able to speak without using its mouth, with a voice emanating from inside its body. “The stone-eater moves,” the girl observes, “and seeing this causes chilly sweat to rise on the girl’s skin. It is slow, stiff. She hears a faint sound like the grind of a tomb’s cover-stone.” This collection features many similarly uncanny moments in which the human integrates with what feels profoundly inhuman. (Jemisin does creepy so well, it’s enough to make you wish she’d try a straight-up horror novel — another genre that could really use more black writers.) The stories here teem with impostors, parasites and hybrids. Sometimes they must be fought off, but this is one science-fiction author who does not take that stance reflexively. Expand your notion of what we can be, she suggests. Recognize that change is inevitable and often strengthening. Don’t kid yourself that the alternative is safety; the alternative is death.