Stephen King’s “The Dark Tower,” a magnum opus about a haunted gunslinger on a quest for a mysterious spire, stretched out over 22 years, seven novels and 4,272 pages of eerie adventure.

But here’s the really spooky thing: King fans want more.

Now they’re about to get it, although King is taking his readership to a new place that might scare some off. “The Dark Tower: The Gunslinger Born,” the Marvel Comics series, launches this week, and more than 100 retailers are opening for midnight release parties. Despite that intense interest, King knows he will have to persuade many longtime readers that comics are more than juvenilia.

“These comics aren’t junk food; they’re more like delicacies,” King said. “Sushi for the mind, if you like. You have to teach yourself how to read ‘adult comics,’ which are actually comic/novel hybrids ... and even then you have to give yourself to the experience, which means accepting the idea that you’ll need to work a bit as you do with any good novel.”

As with his novels, King’s move into comics is fraught with subplots. One big one: “The Dark Tower” finished with a fizzle in 2004 - many fans complained of a letdown with the saga’s final pages and the fuzzy fate of Roland Deschain, the nomadic hero armed with Winchester revolvers in the face of mutants and magic.

The new “Dark Tower” project provides a chance for King “to make it right,” noted Jud Meyers, co-owner of Earth-2 Comics in Los Angeles, one of the retailers that will be open tonight and into Wednesday morning to sell the comic.

“With the last novel’s ending, there really was a sense of ‘You must be kidding,’ so that certainly adds to the anticipation for the comics,” Meyers said. “This is Stephen King’s first dip into this pop-culture medium, and there’s a lot of excitement. You haven’t seen anything like this in comics, so we’re getting this ‘Harry Potter’-style event.”

Novelists, filmmakers and television writers have been increasingly turning to comics not only as a moonlighting lark (among them “Clerks” director Kevin Smith, best-selling novelist Brad Meltzer, director and BET President Reginald Hudlin and screenwriters such as Miles Millar and John Ridley) but also to take care of unfinished business.

Take writer-director Joss Whedon, whose “Buffy the Vampire Slayer” TV series was canceled in 2003 after seven seasons despite its cult following and unresolved plotlines. Next month, Whedon will deliver his “Season 8,” but it will be in the pages of Dark Horse Comics. Whedon did a similar baton-passing trick when the sci-fi TV show “Firefly” passed off its characters to the 2005 film “Serenity” and a comic book series filled the narrative gap in between. The same sort of tactic also let “Babylon 5” creator J. Michael Straczynski extend that nixed TNT series into comics.

As popular as Whedon is with genre fans, King is among the strongest brand names in American pop culture, so Marvel and retailers are hoping for a “must read” moment for comics, which have lost ground in the video-game era. “Dark Tower” has a large initial printing, and the first issue is projected to sell well above 200,000 copies, according to Dan Buckley, publisher of Marvel Comics.

“Absolutely, we will be selling to people that don’t usually buy comics,” Meyers said.

“This is, in a sense, an origin’ story, and interesting in its own right,” King said in an e-mail interview. “These are not just retellings of books that have already been written. The books serve as a launching pad - and a resource center, I suppose - but the flight is into brand-new territory. People curious about the Crimson King will find things to interest them here. And give them some nightmares, I hope.”

But how much of the new nightmare was dreamed up by King himself?

Comics writer Peter David is credited as scripter, and Robin Furth, King’s research assistant, is also credited. King’s name may be the biggest on the cover, but he acknowledges that the work inside is clearly collaborative.

“I modified their outline and have had a chance to tinker with the dialogue and narration of each issue before it gets graven in stone,” he said. “I don’t tell anyone what or how to draw, though. I know my limitations.”

Limits don’t seem to apply, however, to the public appetite for King’s craft. He’s working on three novels in various stages of completion (a resuscitated 1970s manuscript called “Blaze,” a new work called “Duma Key” and another installment of “The Talisman” with Peter Straub). He also writes a column for Entertainment Weekly and keeps tabs on Hollywood adaptations of his work, which at the moment include a Frank Darabont film of “The Mist” and a TV miniseries of “The Talisman.”