THE FIRST THING you need to know about Dredd is that Karl Urban never takes his helmet off. There's a scene near the end where his space pants are pulled up so high I could draw a topographical map of his balls from memory, but his eyes and forehead retain their mystery.

The second thing to know is that all the bad guys have scars.

The third thing to know about Dredd (note: not in order of importance) is that it's shockingly good. Shocking not necessarily because it's so incredibly good, but because the possibility of it being even slightly good seemed so remote. I mean, imagine someone saying they'd remade Battlefield Earth. That's what Dredd sounds like to most of us only aware of the source material through Sly Stallone slurring "Aayyy yam the law!" in some half-remembered trailer from the '90s.

Even putting aside the history, usually when people tell you that a movie is "Dumb but fun!" it means, "It's awful, but I'm a moron!" Dredd is the exception: It succeeds in finding that elusive mix of tongue-in-cheek camp and visceral thrill. Karl Urban's self-aware rendition of KILL BAD GUY/CATCHPHRASE is Arnold for the modern age, with a backing track of Verhoeven-esque ultra violence. Everyone likes dead bad guys, but usually B-movies screw up by overcomplicating things. (Lockout had 50 confusing MacGuffins and plot twists like the director thought he was making Memento.) Dredd is new-brutalism simple (two FUTURECOPS have to make it out of a drug-lord-controlled, 200-story high-rise, The Raid: Redemption-style), there are just enough tweaks to the tropes that it doesn't get boring, and the posturing is subtle enough that you don't feel like you're watching a Spike TV sizzle reel.

When Dredd tells drug queen Ma-Ma (Lena Headey, AKA Cersei Lannister, AKA Sarah Connor) over the high-rise loudspeaker, "You are not the law. I am the law," it gives Stallone's dopey, apropos-of-nothing catchphrase a believable context. When Dredd throws a bad guy down an elevator shaft, all he does is look down and say, "Yup."

That's all it needs. In fact, that's all this review needs. Dredd: Yup.