One of the great figures in American fiction, Rambo, will be back on the silver screen this week. The Vietnam veteran with a Medal of Honor and a world-scale case of post-traumatic stress disorder is on a mission to avenge the death of young woman abducted by sex slavers in Mexico. The movie — called “Last Blood” — is being billed as the end of the franchise.

We hope not. The latest sequel is too gory and cartoonish, and Rambo deserves a better exit from the epic yarn that began in 1972. That’s when a Canadian writer, David Morrell, brought out the novel “First Blood,” in which he created Rambo and began to reverse the hostility to GIs returning from our war against the communists in Vietnam.

We read the novel not long after it was published in 1972. We promptly wrote a letter to a war-time crony, Jack Fuller (later editor of the Chicago Tribune), and predicted that “First Blood” would become an American classic. The first movie came out a decade later, to be followed by three sequels and, now, a fourth. All star Sylvester Stallone in his greatest role.

In the novel, Rambo, hitch-hiking through a small Kentucky town, is arrested for vagrancy. Locked in a cell, he has flashbacks to his ordeal as a POW. He breaks out of jail and flees to the mountains, where a manhunt unfolds, with the sheriff’s deputies joined by Rambo’s Special Forces commander, Colonel Trautman. In the end, Trautman slays Rambo after Rambo mortally wounds the sheriff.

In the first movie, the story got a new ending. Rambo merely wounds Sheriff Teasle and Rambo himself survives in a denouement in which he’s surrounded and is ordered by Trautman to give up. “It’s over, Johnny,” the colonel tells him. “It’s Over!” Rambo then delivers what must be one of the most powerfully acted soliloquies ever filmed in Hollywood.

“Nothing is over. Nothing,” Rambo keens. “You just don’t turn it off. It wasn’t my war. You asked me. I didn’t ask you. And I did what I had to do to win. But somebody wouldn’t let us win. And I come back to the world and see those maggots at the airport protesting me, spittin’, callin’ me ‘Baby Killer’ and all kinds of vile crap.”

The epithet “Baby Killer” was echoed this week in a New York Times story about the collapse in morale among America’s Border Patrol along our demarcation with Mexico. One agent quoted by the Times says he’s been called a “kid killer.” It has become so bad that Border Patrol agents even stick to friendly restaurants — lest some angry waiter spit in their soup.

“People actively hate us,” another Border Patrol agent told the Times. It wouldn’t surprise us were that the result of editorial campaigns like the liberal papers have been running against President Trump and agencies that enforce our immigration laws. Mr. Morrell, though, doesn’t look at Rambo through a political lens. He’s on a higher, a more literary plane.

We gained a sense of that this week when we spoke to the novelist by phone. When we started to mention the Times story on the Border Patrol, the author cut us off. “I’m with you on this,” Mr. Morrell interjected. He had read the same dispatch and had also recoiled at the epithet about “kid killer.”

Not that Mr. Morrell was predicting that a border patrol agent might eventually go on a Rambo-esque rampage. Nor are we. The vast majority of veterans go on to live well-adjusted lives back home. What we took Mr. Morrell to be expressing was simply a note of sympathy and understanding for our GIs and veterans, of all wars, and what they went through.

That is what lifts Rambo to immortality and may be why, in its 47 years, the novel “First Blood” has never been out of print. Mr. Morrell was horrified by “Last Blood,” in which he did not collaborate. Maybe he’ll be the one to write a final last chapter, in which Rambo is once again mortal. It may be that, as our hero said, “nothing is over” — but how fitting it would be were Rambo redeemed by his creator.