This review may contain spoilers.

As fans will no doubt be aware, splicing dark threads into the Superman mythology is not an easy thing to get right. For every "Vessel" there is also a "Doomsday."

Undisturbed by recent failings in the dark storytelling arena, "Smallville's" ninth season defiantly pushes forward with more sinister stories of loss, destiny and a horde of DC villains. "Metallo" springs forth with a name guaranteed to draw some interest from the genre: Brian Austin Green.

Thanks to his stint in "Terminator: The Sarah Connor Chronicles," he has a reputation for a hard man with a heart of gold ... only on "Smallville" he'll be trading it for a Kryptonite core. For the uninitiated, this adventure skirts close to the "Silver Age" tale of the Metallo origins with only a handful of details smudged.

We are gently introduced to John Corben, and glimpse only hints of his lost love. Green has an aura of genuine nice-guy charm about him, so much so that you almost dont want to see his transformation into a villain (similar to Davis Bloom last year). After some idle patter on the phone with his new desk mate, Lois (Erica Durance), he steps onto the road only to be hit head-on by a truck. What follows is a harshness that can be described as un-charted territory for "Smallville." Metallic heartbeat tones are pumped into scenes of Corben drowning in his own blood at the side of the road - at no point do we see the full extent of his injuries but his gasps and splutters are enough to say it all ... it's bad. His vision blurs and begins to darken ... and then he sees the light.

Only there is no tunnel and no relief at the end - only a stark light bulb in a desolate-looking building filled with cases and basic medical instruments. The horror-style atmospheric music continues as he awakens; his bandages are blood soaked and his cries for help go unaided ... then he looks at himself in the mirror and Metallo is born.

It's dark, gory and ever-so-slightly gruesome, and that overall tone continues throughout the episode. Corben himself very nicely sums it up with, "I'm in a nightmare, look at me."

But, in what has become a new formula for "Smallville" to follow, the build-up of the Metallo character is ultimately far more entertaining than his downfall, which is relegated to a quick five minute battle underground that is somewhat reminiscent of the mutant-teenager fights from the shows freshman year.

What Worked

Without a doubt, it is Green who carries the episode and provides a sense of reality to Corben throughout his ordeals. When glowing green meteor rock and copper piping could lead to unbelievable antics, Green's accessible character grounds the banter and action. His cameo appearance in the season opener only helped to settle his character allowing for the origins of Metallo to take place.

What elevates him from a villain-of-the-week status however is the impact he has on Lois, who is for all intents and purposes panging over the loss of Clark (Tom Welling). His wise-cracking nature makes the absence of Clark all that more noticeable, creating the illusion that the farm-boy turned journalist has indeed been replaced. Not to mention his animosity towards The Blur only helps spur on Lois' resistance to the acceptance that Clark is gone. It is for this reason that the Lois/Blur exchanges again become such a delight, this time building to a semi-meet between the duo.

The growing triangle between Clark, Lois and Chloe (Allison Mack) may feel a little familiar to long time fans who watched a similar setup in the early years, however this time the prize is sidekick status instead of Clark's heart. But when Clark finally turns to Chloe for help, their efforts in piecing together the life of John Corben is touching and goes a long way to emphasis the feelings Chloe has herself. The Blur failed to save Corben's wife and now he resents him for it - what gives The Blur the right to play God and decide who should live and who should die? Chloe is in the same situation following the death of Jimmy at the hands of Doomsday. Corben became a villain consumed with rage, will Chloe walk the same path?

Scenes of criminals tied up in the most unlikeliest of scenarios for the police come as a dose of comedy but also serve as tangible evidence that The Blur is at work in Metropolis. Green Arrow should be proud of what he has unleashed as this is exactly the kind deeds he was encouraging Clark to carry out for the last few years. Clark is done waiting for trouble to land in his back yard.

And, the damsel being knocked unconscious at the most convenient time is just classic "Smallville."

What Didn't Work

Metallo, a real life Terminator, is eliminated after a single episode when he could have amounted to bigger and better things. Only two episodes have aired, but already Metallo has surpassed Maj. Zod (Callum Blue) in the cool-villain contest. Plus, his cameo appearance in "Savior" hardly counts as a two-episode arc.

Again, Alessandro Juliani is given absolutely nothing to work with and his character does more harm than good. One might even suspect that he is a Krypto-freak with the ability to make snap-diagnoses with a three-second glimpse. As Corben is brought into the ER, he casually looks him over and is able to provide an assessment of the situation: someone has implanted bionic matrix into his chest and it is powered by meteor rock. What's more, he instantly knows that his heart has been removed and the device is the only thing keeping him alive.

It are these kind of info-dump moments that prevents "Smallville" from being taken too seriously and the show is certainly capable of serious stuff.

Giving Credit Where Credit Is Due

"Smallville" stars Tom Welling, Erica Durance, Allison Mack, Justin Hartley, Cassidy Freeman and Callum Blue. "Metallo" was written by Don Whitehead and Holly Henderson. The episode was directed by Mairzee Almas.

"Smallville" airs Fridays at 8 p.m. ET on The CW.