Can someone please put John Rambo out of his misery? The ’80s franchise has long since grown cold, but in an era of reboots and sequels, it’s no surprise that some might try to squeeze one last money drop out of this title. But in this haggard, sorry state, here’s hoping “Rambo: Last Blood,” lethargically directed by Adrian Grunberg, is the end of the line for Sylvester Stallone’s once-iconic character. Rambo lumbers to the finish line in the flaccid fifth installment, which is a Frankenstein’s monster of badly photocopied references to the previous movies, limply strung together with the laziest of screenplays.

This time, it’s not Vietnam, Burma, Afghanistan or even the U.S. that has drawn John Rambo’s ire, but Mexico. John’s living a quiet life on an Arizona ranch, keeping a protective eye on young Gabrielle (Yvette Monreal), an adopted niece of sorts. When Gabby runs away across the border to find her birth father and ends up trafficked into sexual exploitation (a turn one can see coming from a mile away), woe upon the gangsters who kidnapped her. Rambo’s gonna rip their collarbones out one by one.

“Last Blood” is deeply, topically xenophobic. And while the “Rambo” films aren’t exactly known for their international diplomacy, the hackneyed, poorly executed racial stereotypes and sexual violence to which Gabriella is subjected is just offensively lazy screenwriting.

The whole script is lazy. It’s barely a script at all. Writers Stallone, Matthew Cirulnick and Dan Gordon trade on charged imagery rather than, you know, actually writing characters that fully express the spectrum of human morality. “Good vs. evil” is an idea that John, who articulates himself like he’s endured one too many traumatic brain injuries, is obsessively hung up on, in that sometimes he monosyllabically grunts about “bad guys.”

You have to feel for him. And we might be able to, if the film at all explored the PTSD he tries to treat with fistfuls of mystery pills, obsessive horse training and wholly unnecessary blacksmithing. Rather than exploring the interior world of an aging Rambo, “Last Blood” is preoccupied with the “Home Alone”-style traps John sets up in the tunnels beneath his farm in an extended montage that becomes ludicrously outlandish as it progresses. A spike! More spikes! Lots of shotguns! And knives. A rake! Hay bales rigged to explode! Even more spikes, if you can believe it. There’s a glimmer of hope that maybe, just maybe, the leaden affair will lighten up with some lighthearted bloodshed, but no. As soon as Rambo lures the Mexican sex traffickers into his underground lair, the traps merely slice and dice bodies grimly, joylessly, splattering the saddest pixels of digital blood.

Everything about “Last Blood” is so perfunctory that it makes the film something to be slogged through, rather than enjoyed. It’s right there on Stallone’s face, rendered uncannily unexpressive. He seems the most tired of anyone, going through the motions, trudging through what might hopefully be this character’s last ride. If only anyone involved had made a modicum of effort to make it memorable.