Mr. Gaiman, 56, said he approached the myths as a musician might do if recording cover versions of 1950s folk songs, or as the comedians do with the central joke in the movie “The Aristocrats.” The basic story is there, but how you manage the details is up to you.

So he included emotions, motivations, snappy dialogue, sly Gaimanian flourishes. He spruced up the roles of the goddesses, who are traditionally poorly treated by the sexist gods but who stand up for themselves in his telling. (“What kind of person do you think I am?” the goddess Freya asks, when she hears about a dubious deal to marry her off to an ogre.)

“I’m trying to write a book that a Norse scholar is not going to go, ‘He’s got it so completely wrong,’” Mr. Gaiman said. “But I’m not telling it for a Norse scholar. What I want to do is tell you the story and make it work as a story.”

He has a great many things going on. He has a young son with his wife, the American singer Amanda Palmer, who matches him for antic subversion. He recently finished writing the scripts for “Good Omens,” a six-part series based on the novel he wrote with Terry Pratchett; the series is to appear on Amazon Prime and the BBC next year. There’s also the eagerly awaited series based on his best-selling book “American Gods,” for which Mr. Gaiman serves as executive producer and which will be broadcast on Starz this year.

His novel-in-progress is a sequel to “Neverwhere.” Just as that book was a “way of talking about homelessness and mental illness and the dispossessed without really talking about them,” he said in the interview, the new work will partly be about the plight of refugees in a city struggling to adjust at a bewildering moment.

“London post-Brexit, and the world, are in a horrible, messy state,” he said, referring to Britain’s vote to exit the European Union. “I can take all the anger that I feel and put it into a book.”

At the Town Hall appearance, Mr. Gaiman treated fans to the official trailer from “American Gods,” as well as to the trailer for a forthcoming movie based on an old short story he wrote called “How to Talk to Girls at Parties.” (“It’s the finest Romeo and Juliet story with punks and aliens set in 1977 in Croydon that has ever been made,” he declared.)