POMPEII Pictured: Jon Snow. Not pictured: Game of Thrones.

THE BEST B MOVIES are always the ones that don't realize they're B movies. They're the movies that draw their bows and aim resolutely for A-list status, then bobble the ball on the way to the finish line. (I think I just jammed metaphors from three different sports into one sentence; you are welcome.) Pompeii aims to be a sweeping, grand, historical epic, and it's a dumb, awkward snooze for its perfunctory first half. But something happens around midway through the movie—SPOILER: A VOLCANO ERUPTS—and the second half of Pompeii, while no less stupid, is goofy and explosive fun.

Jon Snow (Jon Snow) is a gladiator who's sad because Romans killed his entire tribe of Celtic horsepeople. Luckily, he's also really, really good at gladiating, and abs, and not wearing a shirt. One day a pretty rich girl (Emily Browning) passes him with her horse and cart. The horse hurts a paw or something, and she falls in love with Jon Snow because he is a Celtic horseperson and knows how to kill the horse properly. Kiefer Sutherland, meanwhile, is a Roman senator who wants to fuck the pretty rich girl. She does not want to fuck him back because he doesn't know how to kill horses and also he is an evil Roman up to evil things.

A bunch of other crap happens that doesn't include gladiators or volcanoes, but before too long, there is a huge battle in Pompeii's arena. This is where the movie gets very silly and enjoyable: Right in the middle of an already pretty nuts gladiator fight, Mount Vesuvius starts to erupt, and the rest of Pompeii is disaster porn that takes some serious historical and geological liberties. We pretty much know what's going to happen, though, and the crushing inevitability of it all sucks out most of the dramatic tension. But this, after all, is a movie where two men will interrupt their frenzied fleeing from a cataclysmic disaster in order to have a sword fight with each other (this happens more than once in Pompeii), so let's not get all hung up on the nuances of effective storytelling.

It's a little disappointing to discover that Jon Snow is not a very good actor when he's not being Jon Snow, but Sutherland is a campy delight, verging on Nic Cage territory. Browning, too, is awfully nice to look at, even when her hair is caked with layers of volcanic ash. Carrie-Anne Moss does some stuff that I've already forgotten about, as does Jared Harris and one of the guys from Grimm. Lastly, Adewale Akinnuoye-Agbaje plays a fellow gladiator (named Atticus!) and I dare say he's sort of great in this.

Look: Pompeii is certainly not a good, or particularly skillful, or even a wholly competent movie. But for a good 30 minutes, it offers a bugnuts, plotless action ride, as a CG mountain handsomely explodes, and Romans and gladiators try to slice each other to death with swords. Considering that we already know how badly it's going to end, Pompeii tries a lot harder than it needs to. Watching it fail is probably more fun than it would have been to watch it succeed.