From “Sandman: Overture,” by Neil Gaiman and J.H. Williams III. (Courtesy of Vertigo)

NEIL GAIMAN has, at last, arrived at the end of his Sandman beginnings.

The sixth and final issue of “The Sandman: Overture,” the bimonthly series from Vertigo Comics that provides an early look at such Sandman characters as Morpheus and the Endless (who made their 1989 debut in the original Sandman epic from DC/Vertigo) — and that promises to reveal narrative secrets that Gaiman had been holding close to the waistcoat for decades — hits comic stands virtual and physical Wednesday.

The digital version of issue No. 6 will also feature a first look at “The Twilight Children,” a series from Gilbert Hernandez and Darwyn Cooke. Vertigo will release the entire six-issue series of “The Sandman: Overture” in graphic-novel form Nov. 10.

[Calling Neil Gaiman fans: Author’s rarities go on Humble Bundle to back CBLDF]

(courtesy of Vertigo)
(courtesy of Vertigo)

“It was very scary and nerve-wracking,” Gaiman told The Post’s Comic Riffs of completing the new series. “The fundamentals of the story had been there for about 25 years, but it kept not actually happening. The story itself didn’t fit into the actual shape of Sandmans Nos. 1 to 75, so it was always implied.”

“Mostly, it was enormous fun meeting these characters again, getting to write the characters again,” he offered. “They never go away; they just sit in my head.”

One character who oft-floated in Gaiman’s imagination was Dream (Morpheus). “I love Dream. He is so grumpy, and so set in his ways,” Gaiman said. “So this is a story that he gets through — with no thanks to him.”

[Gaiman’s hit novel sprung fron an ocean of loneliness]

“The Sandman: Overture.” (courtesy of Vertigo)

Gaiman said he presumes that most people who read “Sandman: Overture” have already read the “Sandman” series. Given that, he said, those who read “Overture” can then dive back into the original series with fresh eyes.

“I think what I love about it most is that if it’s worked, if you read the whole of ‘Overture’ and then read the whole of ‘Sandman,’ things you thought you knew may refer to other events or emotions in ways you weren’t expecting,” Gaiman said.

Bringing Gaiman’s words to visual life on this miniseries has been J.H. Williams III. Gaiman said that Williams had the task of drawing the unthinkable, yet the artist gloriously met each obstacle.

“It was wonderful working with J.H. Williams, knowing that I could ask him to draw impossible things and that he would — he would draw them, and they would be impossible, but they would work,” Gaiman told The Post. “That made me happy all the time, from the very beginning when I asked him to draw Dream as a flower and he did. Quite gorgeous, quite astonishing.”

(courtesy of DC/Vertigo Comics)

Having drawn his final issue of “Sandman: Overture,” Williams said the experience left him “very tired, but equally exhilarated.”

“I hope we’ve miraculously pulled off something special,” Williams said of his work with Gaiman. “The entire thing has been a wonder, really. We’ve got such a grand story, in my humble opinion, the best Sandman story so far, and that I had a place in its creation has been a true highlight of my expanding career.”

Now what awaits fans of this cherished universe is the ability to connect the two series — a reading threshold that the beloved author highly anticipates. “I’m just really interested,” Gaiman said, “in seeing what happens when people read it all the way through.”

A variant cover for "The Sandman: Overture," No. 6. (courtesy of Vertigo)
A variant cover for “The Sandman: Overture,” No. 6. (courtesy of Vertigo)
A variant cover for "Sandman: Overture." (courtesy of Vertigo)
A variant cover for “The Sandman: Overture” No. 6. (courtesy of Vertigo)