"Goodbye, Son," says mom with a hug. "Don't forget to write!"

"Be careful," adds dad.

Whereupon young Pfc. Ed Marks, fresh of face and square of jaw, strides off toward his plane and into America's longest running, undeclared war in Volume 1, Number 1 of Marvel Comics' new series, "The 'Nam."

His Air Force jet is greeted at Tan Son Nhut by enemy tracers. His leering first sergeant wants a bribe in exchange for assigning a cushy duty. By the end of his first 22 pages the private has become acquainted with booby traps, VC tunnels and a squad so combat-hardened that it won't leave a movie screening even under rocket fire. "You're not in the world now -- you're in the 'Nam," a bunkmate tells the stunned newcomer to the 23rd Infantry. "Things are different here."

The Marvelized Vietnam is a darker, more surreal place than John Wayne or Sly Stallone ever visited. "It's much more like 'M*A*S*H' than Rambo," comments Marvel Editor in Chief Jim Shooter.

Marvel, which dominates the $ 175 million comic book industry, is printing about half a million copies of "The 'Nam," which hits the nation's newsstands this week. It's virtually a certain moneymaker -- "We haven't lost money on a book in eight years," Shooter notes -- but it may be more than that. In the comic book specialty stores that now account for close to half of comic sales, "The 'Nam" is outperformingUncanny X-Men, Marvel's number one book. "We've been selling the heck out of it," Shooter exults.

"The 'Nam" makes its debut at a time when the comics industry is becoming noticeably more sophisticated, if not completely respectable. Marvel, marking the 25th anniversary of its founding by seer Stan Lee, is continuing the trend started with angst-ridden heroes like Spiderman. Its Epic comics -- which, with their higher cover prices and slick stock, are aimed frankly at adults -- more closely resemble illustrated science fiction novels than Archie and Veronica romps. Rival DC Comics has unveiled a sensitive '80s makeover of the Man of Steel and a new Batman series (Bruce Wayne has become an embittered vigilante) that has critic James Wolcott raving about its "moodiness and visual acuity" in Vanity Fair. Farther from the mainstream, Chicago's First Comics offers "American Flagg," in which the villains might be ruthless developers set to bulldoze a ghetto to build a shopping mall; "Maus," from New York's Raw, presents a Holocaust allegory based on the life of the artist's father.

Accordingly, "The 'Nam" has little in common with traditional war comics, which are full of unlikely heroics and unambiguous victories. "People are more open to seeing the down side, a fuller picture," says Marvel's Larry Hama, editor of "The 'Nam," "rather than that happy-go-lucky jingoism."

Hama, 37, and the book's writer, Doug Murray, 38, are Vietnam veterans with a honed skepticism about the glories of war. (Shooter, 34 -- despite the apt surname -- was spared during the first draft lottery.)

Murray (whose script is illustrated by Florida artist Michael Golden) was drafted in 1968 when he lost his student deferment after missing a semester at Columbia because of a basketball injury. In his four years as an Army staff sergeant, he did two tours of Vietnam, a total of nearly a year in what one of his characters now acerbicly calls "The Jewel of Southeast Asia." Politically "fairly neutral" when first drafted, Murray says his feelings about the war fluctuated: He was "sort of pro-war" after the Tet offensive, spent several months recuperating from shrapnel wounds received in an ambush during his first tour and grew more doubtful during his second tour in 1971.

But the men from Marvel insist that "The 'Nam" will largely ignore politics; it is meant to be a grunt's-eye view. It will unfold in "real time," one 75-cent book per month for the next eight years, covering the years 1966 to 1974. And it is, Murray insists, "a pretty accurate view of the way the average soldier looked at the war. It was outside ordinary experience. The world was elsewhere."

In the interests of realism, Pfc. Marks will be rotated stateside after 12 months -- Murray plans to send him to college and perhaps have him return to Vietnam as a war correspondent. The actions of the 23rd Infantry will be based on fact. Characters will die. "People will get fragged, I can guarantee that," Murray adds. "It happened in every unit." Bob Hope and Jane Fonda will make appearances, but little will be seen or heard of the military brass. "I doubt a ground-level troop would ever see Creighton Abrams or Westmoreland," says Murray, who didn't. A back-of-the-book glossary explains the characters' authentic lingo, though the comic book " 'Nam" lacks the obscene language of the real thing. (Otherwise it couldn't carry the Comics Code Authority seal of approval).

Judging from the first batch of reader mail, the comic's buyers seem a diverse group: teen-agers not yet born when Pfc. Marks had his first firefight; sons of veterans; collectors; a vet from Alabama explaining in three typed pages why he found the portrayal of the corrupt sergeant offensive; a former first lieutenant from Atlanta lapsing into military slang to say, "it's about time someone told the folks back here in the world just how dinkee dow the whole scene over there really was."

Murray, who would like to be able to leave his job as a computer operations manager for Chase Manhattan Bank to become a full-time comics writer, says he anticipates few complaints from fellow veterans, "as long as I portray the war realistically and don't try to grind axes."

Indeed, Marine Corps veteran and former Newsweek editor William Broyles Jr. is among the series' early fans. "They know what they're talking about," he concluded after reading the first issue. "It has a certain gritty reality. And they're not going to shrink from the ambiguities.

"The more people read about Vietnam, the better. This is going to reach a lot of people who aren't going to read 'The Best and the Brightest' or 'Fire in the Lake' " -- or Broyles' own recently published "Brothers in Arms."

But Jan Scruggs, president of the Vietnam Veterans Memorial Fund, was slightly more troubled. Though he also appreciated the book's accuracy and attention to detail, "another side of me thinks, why should Vietnam be the subject of a comic book?"

"The 'Nam" does raise the question of whether there isn't anything too painful, too serious or too sacred to become grist for the pop culture mill. It's a question Shooter's used to answering. "There's a lot of interest now in Vietnam; my sense is that people are ready to look at it ... I would have qualms if I weren't sure the people doing [the book] are qualified."

And speaking of sacred, he points out, Marvel Comics already has published in several languages the official, authorized biography of Pope John Paul II, plus a companion comic about Mother Teresa.

"We got letters saying, 'How dare you put the Pope in a comic book?' To which I replied, 'Hey, the guy wears a cape.' " CAPTION: Illustration, Photograph, (four pages and cover of comic book), (c) 1986 marvel comics groups; Photo, Vietnam Vetern Doug Murray, writer of "The Nam" (Doug Murray), Nancy Kaye for TWP