In disaster movies, the disaster never comes soon enough. Filmmakers tend to sketch the lives and romantic entanglements of their main characters for an hour or so before fate confronts them with an iceberg (Titanic), "an enormous wall of water" (The Poseidon Adventure), an instant ice age (The Day After Tomorrow) or the end of the freakin' world (2012). You're handed reams of character exposition so that, when hundreds or millions are about to die in the utterly random Act of God that finally occurs, you know whom to root for. James Cameron's Titanic took 100 minutes, more than half of its running time, to bring Leonardo DiCaprio and Kate Winslet together so that they could go bobbing for corpses in the second half.
Say this for Pompeii, the surpassingly silly melodrama about the eruption in 79 A.D. of the Vesuvius volcano that destroyed the Roman port city: by that 100-minute mark, the film is over. Director Paul W.S. Anderson, mastermind of the Resident Evil horror franchise, knows that his audience sits through the "people" parts of a disaster movie with the same restlessness and ennui that porn enthusiasts feel during the perfunctory early scenes of a lonely housewife meeting the pizza delivery man. Not for nothing is Pompeii's genre widely known as disaster porn. The requisite orgy toward the end of hardcore smut finds its equivalent in the group kill of major characters, more or less in ascending order of star billing, when Vesuvius has its fatal orgasm. Instead of communal sex, Anderson provides the spectacle of gruesome serial deaths.
(READ: Michelle Castillo on Paul W.S. Anderson's Resident Evil series)
In choosing which story lines to use before the big blow, Anderson and the screenwriters — Michael Robert Johnson (who worked on Robert Downey Jr.'s first Sherlock Holmes movie) and Lee and Janet Scott Batchler (Batman Forever, the awful one with Val Kilmer and Jim Carrey) — must have picked old-movie titles out of a hat. Gladiator is obvious; hence the hero Milo (Kit Harington, who plays Jon Snow on Game of Thrones) imprisoned by Imperial Rome and forced into mortal combat for the pleasure of coliseum crowds. Also, other early-A.D. epics like Quo Vadis (decadent Roman officials) and Ben-Hur (a chariot race). And of course Romeo and Juliet, aka Titanic, for the doomed love of the low-born Brit Milo and the Pompeii princess Cassia (Sucker Punch's Emily Browning).
But into this plot-sorting hat, someone mischievous threw a few ringers: The Princess Bride, for one. Milo, who as a boy in Britannia had watched in horror as his entire clan was slaughtered by the Roman General Corvus (Kiefer Sutherland) and his designated hit man Proculus (Sasha Roiz), ends up in Pompeii during a visit by the two victorious warriors/mass murderers. Though our hero keeps running into this pair of dastards, we have to wait the full length of the movie for him to confront the last-standing villain and say, "Hello. My name is Milo the Celt. You killed my family. Prepare to die."
(READ: Corliss on the legacy of The Princess Bride)
Sure, that reference is borderline plausible. But The Horse Whisperer? Milo is the lone survivor of a tribe of expert equestrians, and as he trudges in shackles toward Pompeii, he sees that a steed drawing Cassia's carriage has been injured. Milo actually whispers to the horse, then deftly snaps its neck. "How did you do that?" she asks in awe, and he replies, "I asked him." Pompeii may be the first movie in which the heroine falls in love with the hero after watching him kill a horse.
Cassia might wish that Milo could perform the same surgery on her: She'd rather die than give herself to her preening suitor Corvus, who had circled her and been rebuffed when they were both in Rome. He is visiting Pompeii with an eye to investing in the infrastructure plans of her plutocrat father Severus (Mad Men's Jared Harris) and to take Cassia as his bride, presumably because her hatred turns him on. The movie presents the weak Severus and his stately-starchy wife Aurelia (Carrie Ann Moss, from The Matrix) as the corrupt antithesis to the Milo-Cassia romance. It so happens that both couples are headed for the same loving final image — two petrified pairs — in a movie that honors genre clichés as if they were divine edicts.
(SEE: Vesuvius as one of the Top 10 Volcanoes — maybe even No.1)
Among these clichés is the one about the sturdy veteran who announces his intention to retire after a last day on the job — that would be the gladiator slave Atticus (Adewale Akinnuoye-Agbaje, best known as the drug lord priest Eko on Lost). He has been promised his freedom when he achieves his next kill — in the arena, against Milo. A decent twist: Rather than fight each other, they stage a two-man rebellion against Corvus' armed legion. Most of the time, Harington makes for a wan hero, with nothing to recommend him except a killer set of abs. But Akinnuoye-Agbaje's gleaming machismo proves contagious: Harington and the film spring to brief, robust life.
It's typical of Pompeii that it keeps swerving between cool action scenes and filmmaking that dwells on the subcontinent of subcompetence. Shots are held a split-second too long, leaving dead emotional air; supporting characters lack the juice that would give them vitality. The slavemaster Graecus should offer a quick rich vignette of waste and derangement, but Joe Pingue squanders the chance. Where is Jay Robinson, the lusciously mad Caligula in the 1953 epic The Robe? All right, he's dead. So go even gayer and call on Buddy Cole (Scott Thompson of the old Canadian comedy series The Kids in the Hall), who lent his own imperial flounce to a Soshi visit on this week's Colbert Report.
(READ: TIME's review of The Robe)
This capricious shuffling of the vigorous and the awful, as if Anderson couldn't tell the difference or just didn't care, keeps the audience off-guard and alert during Pompeii's first hour, when everyone strenuously ignores the warnings of nearby Vesuvius. (It keeps exuding low murmurings, like the tummy growls of the gods.) Milo ignores them, too — odd, since he is sensitive to horses, and they are sensitive to imminent seismic activity. He could have grabbed Cassia and galloped her out of Pompeii a previous few hours in advance — but then, of course, there'd be no Act Three.
In earlier pictures inspired by Edward Bulwer-Lytton's 1834 novel The Last Days of Pompeii, the climactic cataclysm — the only compelling reason, really, for these movies to exist — comes almost as an afterthought. Mario Caserini's 1913 Italian epic, one of the very first feature films, spends 53 of its extant 59 minutes dawdling toward the eruption. The 1959 movie starring Steve Reeves, with direction by Sergio Leone (his helming debut) and second-unit work by Quentin Tarantino favorite Sergio Corbucci, doesn't get to the big bang until the 83rd minute of its 97-minute running time. A 1984 Pompeii miniseries, more than five hours long, made viewers wait four-and-a-half hours for Vesuvius to blow its stack. (All three films can be seen on YouTube; not so the 1935 Hollywood version, with nifty special effects by King Kong stop-motion animator Willis O'Brien.)
(READ: a review of the 1935 The Last Days of Pompeii by subscribing to TIME)
Anderson, to his credit, lavishes the last third of his movie on the volcano's pyrotechnics. Lava spumes from the 3-D screen; fireballs of glowing magma fly like catapult missiles; tidal waves kill hundreds trying to escape by sea, and a Poseidon Adventure-like wall of water chases citizens down a narrow street. The effects may not be historically or meteorologically accurate, but, Zeus knows, they work. The sound track booms with explosions, and the voices of the Lucnica Chorus of Slovakia chant away like keening Valkyries. At the end, the gray crape of volcanic ash drapes the Pompeiians — all but Milo, Cassia and Corvus, who are for now exempt from death because there are scores to settle. A Princess Bride faceoff, and a Titanic kiss before dying.
Last month we got The Legend of Hercules, which, in the bad-movie sweepstakes, was several lengths behind this one; it lacked vagrant vigor, and a weird belief in its power to entertain. These are subtle but important distinctions worth making: between a wildly flawed but fitfully diverting picture like Pompeii and the irredeemable junk pile it could have been — between magma cum loudly and magma cum lousy.