American paratroopers sweeping into occupied France to pave the way for the D-Day invasion face off with Nazi monsters of every variety in this movie from J.J. Abrams’ production house. “Overlord” is a just a glorified B movie—a silly comic-book action-horror flick made with a substantial budget—but it has enough energy to keep you anxious and generate some real whiplash scares. Genre fans will find it a blast, though others will consider it tasteless and crass. (Actually, it’s all three.)

It’s June 5, 1944, the night before the launch of Operation Overlord, and a squadron of Allied planes swarm across the coast to land troops to take out Nazi communications that could stymie the invasion. The focus is on the battalion in one of the planes, tasked with taking out a radio tower located atop a church steeple in an occupied French village. The hard-boiled sergeant (Bokeem Woodbine) emphasizes that his men will have to match their enemies’ single-mindedness, but one of the men, greenhorn Private Boyce (Jovan Adepo), obviously has misgivings about the idea of becoming like the Germans, a moralistic stance ridiculed by the company blowhard, Private Tibbet (John Magaro).

In an opening sequence stunningly staged by director Julius Avery, shot by cinematographers Laurie Rose and Fabian Wagner and cut by editor Matt Evans, the plane comes under withering bombardment and crashes. Boyce survives by freeing himself from his parachute after landing in a river, and watches with anger and disgust as German troops kill the sergeant. He’s restrained from intervening by Corporal Ford (Wyatt Russell), the crusty explosives expert newly assigned to the squad who is now in command, and they join with the few other survivors—Tibbet, shutterbug Chase (Iain de Caestecker) and would-be writer Dawson (Jacob Anderson). One will quickly fall to a land mile.

Fortunately in the woods the others encounter Chloe (Mathilde Ollivier), a young woman from the village who leads them to the house she shares with her darling young brother Paul (Gianny Taufer) and an ill aunt concealed in an upstairs room. They will use the place as the staging area for their assault on the tower—a mission they must complete within hours.

But danger intervenes in the person of vicious Nazi officer Wafner (Pilou Asbaek), who expects sexual favors from Chloe in return for his protection of her brother. Boyce’s intervention forces Ford to take the German captive and torture him for information. Eventually Boyce is sent out to reconnoiter, and what he discovers is a ghastly Nazi experiment being conducted by mad scientist Dr. Schmidt (Erich Redman) to create super-soldiers from the dead, using the corpses of village inhabitants as guinea pigs. In the process he is able to recue another member of the squad, Rosenfeld (Dominic Applewhite), who rejoins the American commandos.

But at Boyce’s insistence, mission creep now sets in, as the goal expands to include destroying the gruesome project as well as the radio tower; the movie morphs into a combination of conventional combat tale and walking-dead horror flick, with effects that call to mind those familiar from John Carpenter’s “The Thing” and its many imitators. It also adds child endangerment to the mix as Wafner escapes and takes Paul along with him back to the lab. All culminates in a big finale in which the Nazi scientist’s experimental serum plays a major role.

Acting is secondary to action and effects in this kind of genre mash-up, but though the dramatic demands made on Adepo are hardly as consequential as those he met in “Fences,” he brings a boyish integrity to Boyce, who serves as the voice of decency, a kind of conscience representing American rectitude—which, of course, is the keynote of the movie’s unabashedly patriotic stance regarding the battle between good and evil. (The same simplicity applies to the picture’s convenient dismissal of the unhappy historical reality that in 1944, the US army was still segregated, and the notion that a black man could have been part of a mission like this would have been be absurd. But presumably dramatic license can be justified as part of the message of American exceptionalism.) And there’s the obligatory soft-heartedness, too: despite his grouchy exterior, Magaro’s Tibbet will ultimately show the American habit of heroic self-sacrifice when it comes to protecting a tyke like Taufer’s cheeky Paul from harm.

On the other side of the coin, Redman and especially Asbaek provide perfect specimens of Nazi sliminess; both of them positively ooze malevolence to the very last breath. And while Russell never quite matches his father Kurt’s facility in playing this sort of no-nonsense he-man, Ollivier manages Chloe’s transition from a beautiful, frightened damsel to determined wielder of a flame-thrower.

No one could say that “Overlord” is a good movie—it’s too ridiculous for that, and doesn’t quite embrace that absurdity to the extent that Tarantino’s more ingenious “Inglourious Basterds” did so memorably. But it’s fun in its own lowbrow way, and makes a nice complement to an undeservedly forgotten lark from 1983—Michael Mann’s goofy “The Keep,” in which Nazi troops in Romania had to contend with an evil force haunting their mountain fortress. A pity that campy effort isn’t readily available in a decent transfer; it could find an audience if it were, as one can be sure “Overlord” will.