As in “American Gods,” the brutality in Neil Gaiman’s “Norse Mythology” feels giddy, cartoonishly weightless, until, suddenly, it doesn’t. Photograph by Nick Cunard / Eyevine / Redux

The gods and goddesses of Olympus are still alive, clomping through our literature, art, and movies. (On the street today, I saw a truck with Hermes on its side—he was gripping a bouquet of flowers, about to convey them to a client of Florists’ Transworld Delivery.) One cannot declare with the same confidence that the Norse gods live among us, despite Wagner, Marvel, and Tolkien (whose elves and dwarves owe much to the Icelandic Eddas). So little of their past endures—only a few medieval manuscripts, written long after Christianity had displaced the stark religions of the North. (Snorri Sturluson, the author of the Prose Edda, was as unlucky as the pantheon that he depicted: a son-in-law murdered him for political advantage.)

These thirteenth-century texts paint only a partial picture of the Aesir deities, who make their home at the stronghold of Asgard. What scraps we have of the frost giants and other inhabitants of the nine Norse worlds are intensely strange, blown in on icy drafts from an elsewhere of heightened bleakness and grandeur. There is a warship made from the untrimmed fingernails of the dead. The first ancestor of the Aesir is born not when some greater god decrees it but when a hornless cow of mysterious origins licks a block of ice until a head appears, and then a body. The earliest humans are crafted from logs of ash and elm that happen to wash up on the seashore. Their carver is Odin, the highest and oldest of the Aesir, who must “sacrifice himself to himself” on the gallows of the world tree in order to attain the full measure of divine wisdom. (Why would he demand such a thing, and how does he know what to do? This cosmology privileges inscrutability and violence.)

With “Norse Mythology,” Neil Gaiman attempts to update such tales for the modern era. Gaiman, a writer of fantasy novels and comic books, is also a celebrity interested in icons and their reception; he has found success in the past by domesticating deities just enough. (His blockbuster novel “American Gods,” originally published in 2001, incarnated Odin as a con artist with a glass eye, and “The Sandman” comic-book series drew deeply on mythological themes.) Gaiman brings rakish mischief and severe glamour to the Norse canon, both in terms of his public persona and his writing style. His Aesir use contemporary diction (“Shut up, Thor”) and slip into Jack Kirby rhythms (“I have a bad feeling about this”). Their conversations are arch, but their surroundings are raw and desolate. As in “American Gods”—which inspired a savage, stylish TV series, released in 2017—the brutality feels giddy, cartoonishly weightless, until suddenly it doesn’t.

“Norse Mythology” employs a curious, childlike tone that seems intended to be polarizing: “Hoenir was tall and good-looking, and he looked like a king. When Mimir was with him to advise him, Hoenir also spoke like a king and made wise decisions.” Gaiman’s intended audience of both kids and adults can’t quite explain away such guileless prose. Either the entire volume is secretly narrated by the not-too-bright Thor, or this is sly provocation, an invitation to compare the modesty of the language with the depths of wit and trickery that it might conceal. Perhaps “Norse Mythology” is actually narrated by Loki, the graceful dissembler with the scarred lips.

Loki—all faux-innocence, churning brain, and casual cruelty—is more than the book’s most alluring character: he also feels like its governing intelligence. The Olympians often had legible, human motivations: lust, envy, pride. The impulses driving the Aesir are not so much base as unknowable, and this truer for no one than for Loki, Asgard’s friend and betrayer. It is Loki who procures for the gods their best treasures—the spear that never misses, the hammer that never breaks. It is also Loki who marshals the monsters destined to destroy the world. Of course, few of the Aesir behave in ways that scan psychologically to the modern reader; even for their Scandinavian worshippers, the rulers of Asgard embodied the forces of a capricious, often inhospitable universe. We encounter them now across a fjord of time and distance. (And Gaiman is happily more tolerant of this estrangement than the Marvel movies, which prefer to orchestrate a torpid chumminess between heroes and audience.) In his foreword, Gaiman laments the lack of detail surrounding the Norse goddesses, including the quick-tempered Freya and Idunn, the guardian of eternal youth. His “close but creative” translation of the source texts, he told Slate’s Jacob Brogan, did not permit him to invent material out of whole cloth. Yet the author does his best to shade and complicate the female characters when they appear. Gaiman’s apology would feel more like a cop-out if every player in this volume did not remain, on some level, achingly remote, as elusive as the dragon that Odin frees to “slither and slip beneath the waves and swim away in loops and curls.”

There is one respect in which the Norse gods and goddesses, rarely as relatable as the Olympians, feel far more human: they die. At Ragnarok, Gaiman writes, an army of giants, fire demons, and underworld wraiths will descend on Asgard. The universe “will end in ash and flood, in darkness and in ice,” and the Aesir will fall one by one. In an essay for the Guardian, Ursula K. Le Guin underlined the Eddas’ essential bleakness. “Judaism, Christianity and Islam are divine comedies,” she observed. “There may be punishment for the wicked, but the promise of salvation holds. What we have from the Norse is a fragment of a divine tragedy.” In refusing to invoke any sort of immortality, the Icelandic cycle sinks into a strange, stately gloom, neither human nor wholly transcendent. These gods do not symbolize eternal life. The comfort that they offer is a chillier one: that of seeing one’s own death enacted on monumental terms.

Such a theatre of apocalypse may seem ill-fitted to Gaiman’s Looney Tunes physics, his delight in meting out violence for a comic, no-real-harm-done effect. The cold core of the source material is the nihilistic knowledge that these glorious characters, like all of us, are living on borrowed time. Gaiman, who elsewhere advises that “the world is always ending for someone,” appears only partially willing to soften this reality. When you choose Norse mythology as your subject, it seems that there are a few truths you cannot escape, even if your love for the characters might compel you to try.

The author does conclude his telling on a note of fragile hope, conjuring a time, post-doomsday, when “the green earth will arise once more.” A few survivors will straggle out onto the field, he writes: Balder, the god of beauty, and two of Thor’s sons. They will find the Aesir’s old chess pieces glittering in the grass, and the statues will be shaped like fallen gods: “Here is Thor, holding his hammer. There is Heimdall, his horn at his lips.” This is hardly a true resurrection—if anything, a chess metaphor quietly suggests that the wars and loves of the Asgardians were never more than a game. But a game is more bearable than a tragedy. Gaiman, who can’t forestall the night, can still whistle in the dark.