Although they'd successfully established a peerless reputation for speed metal mastery with their genre-defining first album, 1985's Skeptics Apocalypse, and similarly blazing follow-up EP, Mad Locust Rising, Agent Steel were facing a significantly different environment by the time they returned to action with 1987's Unstoppable Force LP.

In the span of just a few years, America's heavy metal scene had grown by leaps and bounds and segmented into pretty well-defined stylistic factions, with glam and thrash dominating the polar ends of the spectrum and leaving only a nebulous middle ground that more "traditional" (read: British-inspired) metal bands like Queensrÿche, Savatage, and Fates Warning shared with numerous smaller subgenres.

And with speed metal quickly losing its autonomous identity in the face of thrash's inexorable advance (giving way to power metal in Europe, but clearly headed towards virtual extinction in America), Agent Steel looked to broaden their sound and take their feet off the accelerator on Unstoppable Force.

Mind you, when the band still felt like letting it rip, as they did on the pulverizing title track, "Indestructive," "Nothin' Left," and multiple passages within other songs, few bands could touch them -- certainly none of the aforementioned three.

And while those selfsame bands had been pushing the progressive rock envelope in search of their own distinguishing flavor, Agent Steel chose to look backwards instead, harking to the mightiest heavy metal gods of old (Priest, Maiden, even slow-poke Sabbath) for the classic foundation and incremental melodicism permeating songs like the acoustically introduced "Chosen to Stay," the slow-riffing standout "Still Searchin'," and the instrumental tour de force "The Day at Guyana" (it should be noted that the entire band delivers simply jaw-dropping musicianship from start to finish).

Yes, Agent Steel visited some of the same semi-commercial metal ground as Queensrÿche or Crimson Glory on chorus-focused cuts like "Never Surrender" and "Rager" -- not to mention the shocking closing ballad, "Traveler" -- but there was still nothing conventional about the lyrics written by mysterious vocalist John Cyriis, who claimed (among other things) to be in contact with extraterrestrials and addressed them directly on many of these tracks! Meanwhile, his impressively elastic vocal range and newly acquired flirtation with rolling Rs also praised another hero in the heavy metal constellation, Rob Halford.

In sum, Unstoppable Force appeared set to proclaim Agent Steel's "arrival" to a much wider audience thanks to its stellar songwriting and more approachable sonic aesthetic, but, as history has recorded, its title soon made liars of the bandmembers when they abruptly decided to break up only a short time later due to mounting internal strife.