Before Armenian American art-metal heroes System of a Down hit big with "Mezmerize" last May, political hard-rock albums were usually pretty insufferable, filled with dated rhetoric about the New World Order (we're looking at you, Rage Against the Machine) or formless railings against the Man (everyone else). "Mezmerize" was a revelation, settling the question of what Noam Chomsky would sound like if he fronted a faster, lumpier version of Primus.

System might not have had much new to say about the war in Iraq (the band's against it, in case you were wondering), but it has an absurdist streak to rival Captain Beefheart's and an unerring instinct for the jugular, and never before have such competing instincts been put to such good use.

The group's latest, the excellent "Hypnotize," is intended as a companion piece to "Mezmerize," which was recorded during the same sessions. The staggered release dates were intended to allow fans time to absorb the first disc, and although this may seem grandiose, the band's got a point. But most of the things System does well -- the melodic shape-shifting, the juxtaposition of the zippy and the grotesque -- rely on the element of surprise. Six months later, "Hypnotize," for all its stylistic feints and jabs, can't help but feel almost routine.

It doesn't help that it's the more conventional of the two discs, though with System of a Down, "conventional" is a relative term. There's nothing here as incendiary as "B.Y.O.B.," the hit single off "Mezmerize" that felt like a neutron bomb dropped into the middle of the record. But there's not a lot of filler, either.

"Hypnotize" kicks off with "Attack," a bruising hardcore number that's the most disappointingly normal thing here, even though its machine-gun guitar assault gives way to a lugubrious ballad partway through. Happily, things get progressively weirder: "U-Fig" is a nifty piece of agitprop that indicts "all pathetic flag-waving ignorant geeks" (hey, no one said they were subtle); "Vicinity of Obscenity" begins as full-frontal hardcore and skitters into a chant about bananas and terracotta pie before evolving into a fat-bottomed disco number that asks, "Do we all learn defeat / From the whores with bad feet?" and that's just the part we can print.

Its whirligig time changes and flights of pop opera fancy are both System signatures, though they increasingly seem like things the band does to make sure you're paying attention, a deal sweetener for any teenage kid who sits through the denser political material.

The increasing interplay between the group's singer/human fireplug Serj Tankian and songwriter-guitarist Daron Malakian is a marvel to behold, though even their harmony vocals can't save "Lonely Day," the sort of lengthy, depressing ballad whose well-intended dullness is meant to signal artistic maturity. System is the rare band capable of doing anything it wants (though its members might not have a great future as diplomats): Ballads should be the last thing on its mind.

"Hypnotize" falters only when System turns its attentions to domestic affairs. There's a nasty strain of sexism running through both records (women are inevitably cast as hookers or drug addicts) that puts the lie to any real claim of progressivism. Even for System of a Down, it seems, enlightenment goes only so far.

System of a Down's "Hypnotize," a companion piece to "Mezmerize," is excellent though more conventional than its predecessor.