King Arthur is dead. What now?

With this question, Lev Grossman’s new novel, “The Bright Sword,” joins 1,400 years of storytelling and resoundingly earns its place among the best of Arthurian tales.

The aspiring hero of this epic is Collum, an adventurer who is equal parts naïve and sardonic. He survived a brutally abusive childhood by promising himself someday he’d be a knight under King Arthur, and so, now a young man, he steals a suit of armor, crafts a new life story and sets out to join the Round Table.

But when he arrives, he finds Camelot in shambles. The hero he admired was killed in a battle just weeks earlier.

Ambitious would-be kings and powerful fairies are amassing on the borders. All that remain to uphold Arthur’s legacy are a handful of downtrodden knights and Nimue, Merlin’s apprentice and usurper. (Grossman’s version acknowledges that the Merlin of tradition is a sexual predator, and Nimue, a bold young woman trying to reconcile her Christian faith with her elemental magic, makes a far more interesting mage.)

Thanks to Collum’s boost of enthusiasm for the lost ideals of Camelot, the knights ask for a “great marvel,” which opens a magical portal and sets them on quest after quest in pursuit of … well, they’re not exactly sure. Collum and the knights of the Round Table don’t know what to hope for: A new king? To get the old one back? A new Camelot or the same Camelot or just a Camelot they can survive in?

The book is long, more than 600 pages, and it feels long. The story meanders, but other than a few back story chapters that are, if not unnecessary, perhaps mistimed, nothing feels superfluous. This is a narrative that demands and rewards patience.

Story lines veer from mundane to absurdly fantastical in the blink of an eye. Supernatural contests against devils and the Green Knight contrast with desperate, messy knife fights with humans. Climactic battles happen far before the end of the book, leaving the reader wondering what could be left. (Turns out, quite a bit.) But it’s exactly this weirdness and rejection of expected structure that proves Grossman knows what he’s doing.

Traditional Arthurian legends balance two opposing imperatives: reveling in magical paganism and reassuring us that God is the ultimate and only power in the world. Grossman successfully leans into this fundamental contradiction. One of the best scenes in the novel is an epic battle between the devious Morgan le Fay’s magical forces and literal angels from on high. Collum is initially joyous at the divine intervention and then becomes utterly bereft as he realizes that none of it matters. All these otherworldly powers are incapable of caring about human life and ultimately two sides of the same coin.

The main story line of the novel belongs to Grossman’s newcomer, Collum, as he becomes a knight and joins the search for a king. But he is far more than another inserted character playing in the world of Camelot. His journey is poignant and essential as he moves from trying to become part of a story to realizing that stories are lies we tell to make sense of a reality that defies simple narrative.

The other characters — a compelling collection of knights, jesters, queens, kings and mages — are equally strong. Standouts include Sir Dagonet, a heartbreakingly wrought jester-knight who can’t seem to find any joy in the world, and Sir Dinadan. Dinadan is one of the best knights to come out of modern Arthurian tales, with a story proving sometimes the best marvels are the ones we make ourselves. He gets the novel’s last line, a startlingly perfect sentiment that had me teary. The one exception to the expertly updated characters is the aforementioned Morgan le Fay. Grossman never quite knows what to do with her power and anger. But that’s a minor quibble, given the complexity, depth and sheer volume of the cast of characters.

Grossman, who is best known for his The Magicians series, is at the top of his game with “The Bright Sword,” which is full of enviable ideas and execution. Few authors could accomplish what he has, grounding such an ambitious novel in so much tradition and history while still making it accessible and deeply affecting.

This Camelot is far more diverse and thoughtful than past iterations. It’s also way more depressed. None of the characters are who or where they hoped to be in their terrifying, Arthur-less world. With their leader gone, so, too, are their dreams of transformation.

The valiant, weary adventurers in this tale never know quite what to hope for, but that might be the point. They just keep hoping anyway. We didn’t need to know what happened after Arthur died, but Arthuriana is far richer for the fact that Grossman, like countless storytellers before him, couldn’t let the dream of Camelot go.