Parsing the truly scary

Science fiction has the rare privilege of being able to borrow from other literary sources without having to sacrifice too much of its own internal logic. The supernatural workings of gothic and ghost stories offer interesting possibilities. While science fiction is not known for its subtlety, its literal tendencies can get in the way of creating a sense of unease, nuance, or dread. Two collections of short stories illustrate this, to good -- and ill -- effect.

In ''The Banquet of the Lords of Night and Other Stories," a collection of wonders by Liz Williams, spirits and demons are everywhere; in the drawing room of William Blake, in the nightly bed of a war criminal, and in the computer mind of future China, where the ''ghost in the machine" takes on literal meaning. It's this very literalism that makes Williams's stories terribly fun to read, although not always driven by the pathos she hopes for. Myths and legends intrude into the real world, but when they become subject to the same natural laws, their supernatural qualities are made banal.

Making the unreal too real has the effect of taking the chill out of it. This approach works in the hard-boiled detective tale ''Adventures in the Ghost Trade," in which Williams herself doesn't take it too seriously. Here, a magic-wielding gumshoe searches for the spirit of a dead girl. During his quest he encounters demons who are vice cops as well as a prevailing view of hell as just another red-light district.

Another story begins filled with atmosphere -- a dying Chinese opera star must fulfill her end of an infernal bargain -- but the story quickly turns into an episode of ''Buffy the Vampire Slayer" as the character describes the geography of hell not as a vision, but as a real place with offices and administrators.

In ''The Daykeeper," the myth of the changeling is brought into the modern world as the creature who replaces a human child finds she is incapable of living among us. Williams asks the literal what-if question, and this mythic faerie creature becomes today's heroin addict.

Williams is more fully in control, however, when the myths and legends she is conjuring remain somewhat elusive. In ''Outremer," a woman is haunted by a promise made to take her from a life of abuse and imprisonment to the joyous release of death. In ''A Child of the Dead," the physical body can be forsaken to join the spirits that inhabit the Internet. Although technology is the theme, the story still reads like a classic ghost story.

The title story is Williams at her strangest and her best. In some future or alternate Paris, an otherworldly royalty keeps everything in darkness, while the very city has turned into a servant class to wait on them. A chef fights back with the only means at his disposal, a meal made deadly by a precious ingredient. The absence of light is skillfully made figurative, and this gives the story its resonance. It's also what gives a ghost story its power to chill, even when inhabiting the often literal worlds of science fiction.

Pamela Sargent -- a longtime writer of speculative fiction -- has a new story collection that shows off her prowess. ''Thumbprints," which includes 12 stories, is an example of how nuance often works best.

The first tale, ''Gather Blue Roses," describes the plight of a young girl with a kind of paranormal empathy, given form by the legacy of her Holocaust-survivor parents. The story is a brooding meditation on what it would be like to literally feel the pain of others, the result being that so much suffering would prevent time from acting as a buffer.

This theme is also woven into another tale, about a young Mongolian woman who tries to protect her tribe from the ghost of her grandmother, who wants to stop the reign of Genghis Khan before it even begins. Here, the spirit world is a literal manifestation, but Sargent describes it as if in a dream, conjuring an unreality that makes for a more fascinating tale.

The title story is the weakest, a literary murder mystery that, while possibly enjoyable for Sargent to write, was not so to read. She changes the names of the victims -- real authors and their books -- in clever ways, and for a while the game of figuring them out is amusing. (Sargent has particular morbid fun with a Dave Eggers doppelganger.) But it's not enough to make up for a tedious plot. Sargent's writing is well crafted, and is most capable when focused on character.

In one of the more riveting stories, ''If Ever I Should Leave You," two lovers in a society of near immortals find that 300 years of living together is still not enough, and use a time machine to prolong their last moments together. It's a moving and romantic tale, and uses speculative tropes to maximum effect without sacrificing the characters.

Peter Bebergal is a writer living in Cambridge. He can be reached at pbebergal@yahoo.com.