At the end of May I found myself on a voyage across the Atlantic aboard the Queen Mary 2, a mere week before the 80th anniversary of the D-Day invasion. Among the passengers were several World War II veterans. Four of them were well over the century mark, and another four were 99. My own grandfather was in Normandy in 1944, so to be traveling with the veterans was humbling, to put it mildly.

One of the highlights for me was listening to the stories of Harold Radish, a Jewish man who grew up in 1930s Brooklyn before shipping out to the war and, after a series of harrowing experiences, ended up in a German POW camp. Radish was nearly 100, but still witty and sharp, with a voice that was a dead ringer for the late Stan Lee. He was a piece of Living History.

The legendary cartoonist Jules Feiffer is only four years younger than Radish. Just a bit too young to be claimed by the war, but old enough to be shaped by it. He is of the generation, so to speak.

And now, with a lifetime of achievement as a playwright, screenwriter and novelist — a Pulitzer and Oscar winner with a place in the Comic Book Hall of Fame — here he is with a middle grade graphic novel called “Amazing Grapes.”

As a storytelling format, the middle grade graphic novel seems ubiquitous now. It’s easy to forget that 25 years ago there was barely such a thing. There was “Bone,” sure, and manga, and there were collections of Scrooge McDuck. But there was nothing like Dog Man, InvestiGators, Amulet, Smile.

Feiffer had a whole career before middle grade graphic novels had shelves of their own.

His new book is wondrous in its own right, but with it we also get a glimpse of what we might have seen if titans like Shel Silverstein, Maurice Sendak or Tomi Ungerer had tried their hand at a book-length comic.

“Amazing Grapes” tells the story of two siblings, Curly and his sister Pearlie, whose adventures begin a year after their father walks out. Their mother has informed them and their older sister, Shirley, that they’re going to have a new father, named Lenny (who has three “younger than you” children: Penny, Benny and Kenny), and soon they’ll all be living with him on a mountaintop halfway across the country.

When moving day comes, the siblings take one last tearful look at their empty house and, with the abrupt shifting of a dream scene, find themselves staring up at an enormous two-headed swan impatiently waiting to fly them to “the Lost Dimension.” Just like that, the eager-to-escape Curly and Pearlie are whisked away to a madcap world.

But “Amazing Grapes” is also the story of Shirley, who refuses the call to adventure, and their disconsolate mother, who is haunted by her own past.

In the Lost Dimension, a place of prismatic colors and vague backgrounds, danger is everywhere. One situation rolls into the next with unpredictable suddenness; nothing is as it seems. Monsters become friends and change size, but still live to betray. Guide dogs are cats in disguise. Heads fall off and are found again. Like Alice’s Wonderland, the Lost Dimension is a topsy-turvy realm of living metaphors.

There’s a dark edge to the story, too, in that the children seem used to instability and ever-shifting rules. They’re drawn with the same wide, haunted eyes as their mother — eyes that knew fear well before being carried to a fantasy land.

As wacky as the story is, the emotional undercurrents that govern the characters are deep. Feiffer knows that life is rarely safe and doesn’t make a lot of sense. Loneliness, betrayal, neglect, selfishness and love are all in the mix. The young siblings struggle to cooperate, even to be civil, while their older sister navigates her relationships to her mother and her own soon-to-be husband.

That Feiffer is still working, and pushing art solidly into new places, with this kind of energy and depth, at 95 is something to celebrate. It’s inspiring.

My 13-year-old daughter was with me when the advance copy of “Amazing Grapes” arrived. So when she murmured “wooaahh …” as she flipped through the pages, my ears perked up. She’s seen a lot of graphic novels, but there was a note in her voice that said “here’s something new.”

A new vintage from a venerable vineyard.