Judas Priest's major-label debut Sin After Sin marks their only recording with then-teenage session drummer Simon Phillips, whose technical prowess helps push the band's burgeoning aggression into overdrive.

For their part, K.K.

Downing and Glenn Tipton employ a great deal more of the driving, palm-muted power-chord picking that would provide the basic rhythmic foundation of all but the most extreme heavy metal from here on out.

Sin After Sin finds Priest still experimenting with their range, and thus ends up as perhaps their most varied outing.

Yet despite the undeniably tremendous peaks here, the overall package doesn't cohere quite as well as on Sad Wings of Destiny, simply because the heavy moments are so recognizable as the metal we know today that the detours stick out as greater interruptions of the album's flow.

The proggy ballad "Last Rose of Summer" is the biggest departure here, with florid lyrics and "red blood/white snow" imagery that would be fully at home on any goth rock band's most depressing bedsit dirges.

"Here Come the Tears" is musically dissimilar, with heavy guitars and Halford's downcast wailing, but it's just as lyrically mopey.

These two sit rather uneasily against the viciousness of the more metallic offerings.

Classic opener "Sinner" is packed with driving riffs, sophisticated guitar interplay (including a whammy-bar freakout during a slower middle section), a melody that winds snakily upward, and nifty little production tricks doubtless inspired by Queen.

A galloping, fully metallic reimagining of the Joan Baez folk tune "Diamonds and Rust" is a smashing success, one of the most effective left-field cover choices in metal history.

"Starbreaker" is the first of many "alien monsters from the sky!" tunes in the band's catalog.

Proggy, churchy guitar intro "Let Us Prey" quickly leads into the speed-burner "Call for the Priest," which may just be the earliest building block in the construction of speed metal, and features some of Tipton and Downing's most impressive twin-guitar harmonies yet.

"Raw Deal" is a less immediate metal offering that faintly recalls the band's blues-rock roots, though it may be most interesting for the blatant lyrical references to S&M bars and gay haven Fire Island, not to mention an unmistakable endorsement of gay rights.

Things close on a high note with the utterly stunning "Dissident Aggressor," one of the heaviest songs in the band's catalog, so much so that it was covered (and not outdone) by Slayer.

Once the bludgeoning main riff abruptly kicks in, Halford screams at what must be the very top of his range; a completely manic Phillips offers some of the earliest double-bass drumming in metal; and the crazed guitar solos prove that Tipton and Downing had more than just pure technique at their disposal.

It's not a stretch to say that at the time of its release, "Dissident Aggressor" was probably the heaviest metal song of all time.

It's the biggest sign here that as good as Judas Priest already was, they were on the verge of something even greater.

In what must seem like a much bigger oddity now, the inaugural American tour that ensued found them opening for REO Speedwagon and Foreigner.