Brawny Greek hero Hercules might be a remarkably powerful fellow in legend, but he’s never shown much cinematic punch in the movies. First came the amusingly awful Italian pseudo-epics with Steve Reeves in the late fifties and early sixties, followed—after dozens of appearances in schlocky beefcake Euro-cheapies in their aftermath—by the even worse Lou Ferrigno embarrassments of the 1980s. And that’s not even counting the unintentionally hilarious “Hercules in New York” of 1970, in which the young Arnold Schwarzenegger (billed as Arnold Strong) was actually outacted by Arnold Stang. True, the animated Disney musical of 1997 had some charm, and the Kevin Sorbo TV series had its moments, but both of them gave the poor guy a tongue-in-cheek twist.

Not so “The Legend of Hercules,” in which hunky Kellan Lutz, of the “Twilight” series, dons the muscular Hellene’s sandals. An “origins” tale that owes less to classical mythology than to current comic book and super-hero conventions and played with an earnestness that’s positively deadly, this unholy mash-up of “300” and “Gladiator” manages to include only one of Hercules’ famous labors—the duel with the Nemean lion, and that as a throwaway—but seems to drag on for an eternity.

The one aspect of the ancient mythology that the script retains is that Hercules is the son of Alcmene (Roxanne McKee) by the god Zeus. But from there on all is cobbled together from other sources. His birth infuriates Alcmene’s husband King Amphitryon of Tiryns (Scott Adkins), a brutal tyrant who’s first shown conquering Argos by defeating its ruler in single combat. The king passes on his hatred of the boy, who’s named Alcides, to his older son, the cruel and cowardly Iphicles (Liam Garrigan), for whom Amphitryon arranges a marriage with Princess Hebe of Crete (Gaia Weiss) despite the fact that Hercules loves her—a passion she reciprocates.

To get rid of the unwanted Alcides, Amphitryon sends him, along with general Sotiris (Liam McIntyre) and a battalion of men, to Egypt, where an ambush awaits that’s supposed to kill him but instead wipes out rest of the company while leaving the two of them alive. They find themselves enslaved as gladiators, first in literally underground games in Egypt and then in Sicily (which, in fact, would not historically be colonized by Greeks until nearly half a millennium after 1200BC, when this story is supposedly set) before they’re brought back to Greece. There Hercules wins his freedom by defeating the six greatest champions from the entire peninsula in one fell swoop. Then he undertakes a rebellion against Amphitryon which, incidentally, will also free Hebe from imminent marriage to Iphicles. His victory ultimately depends on his willingness to finally accept Zeus as his father—as well as daddy’s lightning power added to his sword, which will allow him to vanquish an entire army with some supposedly cool CGI sparkly effects.

All this silliness is presented by director Renny Harlin, in yet another step along his career decline, with a distinct lack of panache but lots of intrusive slow-motion and freeze-frames in the frequent action sequences. It certainly doesn’t help that absolutely none of the picture’s physical backdrop looks remotely real; everything—mountains, buildings, interiors—is CGI-based, so that the film resembles a succession of painted cartoon panels, though ones poorly rendered by the dimming effect of 3D. The actors are authentic human beings implanted in the settings via green screen technology, of course, but it’s hard to tell that from the performances, which with one exception—McIntyre, who actually brings some emotional shading to Sotiris—are uniformly terrible, though in different ways. On the one hand are Lutz and Weiss, whose clumsy poses turn them into expressionless marionettes and whose delivery of the puerile dialogue is hilariously flat (Weiss in particular sounds badly dubbed). At the other extreme are Adkins and Garrigan, who chew the phony-looking scenery so strenuously that they come across like silent-movie villains. Then there’s Rade Serbedzija, who lurks about as aged royal advisor Chiron and mumbles his dialogue in an accent so thick that it makes Lutz sound almost normal.

It’s difficult to assess the contributions of the technical crew in a picture like this, which depends so heavily on the effects team. Suffice it to say that cinematographer Sam McCurdy, though hobbled by a 3D process that might allow projectiles to be hurled at the audience but darkens and smudges the images , seems to have done a reasonably good job, and Sonoo Mishra’s costumes only occasionally appear ridiculous. The score by Tuomas Kantelinen is predictably thunderous but forgettable.

Hercules will get another chance to shine on screen later this year when Dwayne “The Rock” Johnson plays him in Brett Ratner’s big-budget take on the character. MGM and Paramount, however, have every right to be concerned that this stinker might doom any hope for a franchise before their picture arrives in mid-summer.