A Spanish Civil War action comedy with nationalist fascists, anti-fascists, Nazis and zombies, “Valley of the Dead” is the epitome of “high concept,” a movie so simple you can sum up its plot and/or potential appeal in a single line.

It leans more towards the “thriller” end of the spectrum, never quite sticking the zombie comedy landings, never getting all it can from combat-thriller-as-zombie-movie tropes and situations.

But you know the old saying. “If you see one Spanish Civil War zombie action comedy this year…”

Miki Esparbé of “Off Course to China” stars as Capt. Jan Lozano, whom we meet trying to wisecrack his way out from in front of a firing squad. Lucky for him his uncle (Manuel Morón, not a typo) is a general.

The perpetual screw-up, a hot-head who head-butted a judge who happened to be Generalissimo Franco’s cousin is given one last chance, a mission to deliver a message to an officer on the other side of a Republican/leftist held valley. “Suicide,” Capt. Jan gripes (in Spanish with English subtitles, or dubbed).

But he’s assigned a virginal, cowardly driver (Manel Llunell) and off they go. Stopping to check on a fascist pilot whom they see shot down is their undoing. A sergeant (Luis Callejo) and his “anarchist”/leftist militia capture them just as they find the pilot’s corpse.

We have mere moments to get acquainted with “the Russian” (Sergio Torrico) in their ranks, the American photographer and the short-haired/short-tempered fighter named “Priest Killer” (Aura Garrido) when damned if that dead pilot isn’t dead after all. It takes more than a few neck-snaps and bullets to figure out that a shot in the skull is the only thing that stops his crawling, ravenous taste for human flesh.

As their militia’s base camp is wiped out, that makes everyone’s mind up for them. The dead are undead in this Spanish valley. Should they cut their fascist prisoners loose and fight a common enemy?

“You can’t die twice if you don’t escape once,” mutters the Russian Brodsky, given to speaking in proverbs. But as they stumble into other straggling survivors of the zombie mini-apocalypse, there’s nothing for it but to team up — the fascist sniper nicknamed “Muslim” (Mouad Ghazouan) and the bomb-throwing anarchist “Matches” (Álvaro Cervantes) among them — to make it out of that valley alive, or at least unbitten.

Some of the dopey stuff plays. The cowardly virginal Decruz picked a side in the civil war based on his love of the pastries the nuns make in his home town. Can’t be fighting for the anti-Catholics, can he? He’d lose his pastries.

“Priest Killer” whispers how she earned that nickname, as if we can’t guess.

The SS officer/doctor in charge of the “experiment” that got out of hand is played by the tallest screen villain (Francisco Reyes) since Richard “Jaws” Kiel retired. That’s kind of what they were going for here, a gory zombie picture with one-liners and towering sight gags.

The only times this “Valley” seems to come together are when it’s playing with classic combat and horror tropes — “experts” in this or that part of the mission, noble sacrifice, the squad breaking up into units of two or three to go off and fight the zombie horde, each in his or her own way.

The zombie swarms are OK, if nothing new, and the head-burst/cranial spray effects are digital and kind of “meh.”

The acting is pretty good, but the screenplay lacks the jokes and sight gags that would make this sing. The entire enterprise feels somewhat flat-footed much of the time. It’s never remotely as scary or visceral as “28 Days Later” or laugh-out-loud funny at the other extreme, “Zombieland.”

Still, one can appreciate the Spanish Civil War setting, with a script that strives to point out that Italians and Germans, Muslim Berbers from Morocco and Americans were all mixed up in Spain’s ugliest hour, either as combatants, financiers or journalists.

It’s a pity co-directors Javier Ruiz Caldera and Alberto de Toro, who collaborated on the Spanish action comedy “Spy Time,” couldn’t find something funnier to do with this. Hunting for thrills or laughs in this “Valley” proves to be futile.

Rating: TV-MA, mucho violencia. Y profanidad.

Cast: Miki Esparbé, Aura Garrido, Luis Callego, Álvaro Cervantes, Manel Llunell, Mouad Ghazouan, Francisco Reyes and María Botto

Credits: Directed by Javier Ruiz Caldera and Alberto de Toro, scripted by Jaime Marques Olarreaga. A Netflix release.

Running time: 1:41