Clark (Tom Welling) urges Tess (Cassidy Freeman) to stop running scary stories in the Planet about Davis/Doomsday (Sam Witwer). She tells him to shut up and embrace his destiny, since he's going to have to kill Davis sooner or later anyway. While she's talking, he picks up Chloe's (Allison Mack) cries for help and zips off to save her. He's followed by Plastique (Jessica Parker Kennedy) and several other members of Tess's secret super-powered hit squad, hoping that he will lead them to Doomsday. Chloe is apparently working with them.
Safe at the Kent farm, Chloe reveals just how freaky-obsessive Davis became while they were on the road together. She abandoned him when they stopped for gas, believing that there is no longer any good in him. She tells Clark he needs to kill the monster before it hurts anyone else. Clark proves he truly is Superman by declining to remind her that he could have sent Davis to the Phantom Zone last week had certain misguided blonde ninnies not interfered.
Meanwhile, Tess's gang finds the grisly remains of one of their own, Neutron, who ran afoul of Doomsday while attempting to tail the beast. A second member, Livewire, expresses doubts about continuing the search. Tess responds by telling Parasite (Brendon Fletcher) to suck her dry. He and Plastique then resume the search for Doomsday alone.
Over at the Watchtower, Clark tells Oliver (Justin Hartley) his cunning plan for catching Doomsday. Tess keeps a sample of black kryptonite in her vault. Clark can't get it because there might be regular kryptonite nestled alongside of it, but Oliver should be up to the task, and Oliver agrees. Clark tells Oliver that the black kryptonite will kill Davis. In truth, it will split Davis from Doomsday, allowing Clark to save Davis and send the beast to the Phantom Zone. Chloe isn't down with that plan and again urges Clark to kill Davis.
Dr. Emil (Alessandro Juliani) calls Clark with word that Doomsday has struck again. Clark and Tess arrive at the scene to find the remains of Neutron… and Livewire, whom Tess apparently killed with a neural implant. Chloe excuses herself and calls Parasite, asking what happened. He and Plastique tell her that Livewire was alive when they left the scene, and refuse to believe that Tess could have pulled the trigger. Clark finds Chloe back at home and asks why she ditched him at the crime scene. She tells him about Tess's super-powered team, only to collapse dead when her own neural implant is activated. Turns out, she's actually Tess's former assistant Eva (Anna Williams), who has the power to shapeshift and had been impersonating Chloe all along.
Over at the Planet, Oliver shakes down Tess with a bottle of wine and a dazzling smile. Tess isn't buying it, but she does leave a fingerprint on the wine bottle, which Oliver can use to bust into her vault. Meanwhile, Clark tracks down Plastique and offers to help, but when she hears that Tess put a bomb in her head, she decides that killing Tess is a much better idea. Parasite gets the drop on Clark and sucks away his powers before he can stop them.
Their mission of vengeance coincides with Oliver's attempts to secure the black kryptonite. He nabs the stone, but is knocked unconscious when Plastique blows a hole in the wall of Casa de Lex. Parasite used Livewire's powers to short out their kill switches, which means Tess can't blow their heads up. They tell her to give them the files on the other Black Creek inmates, planning to form a new league of supervillains. A depowered Clark arrives and tries to stop them, urging Plastique to follow the better angels of her nature. Plastique is having none of it, however, and Parasite is happy to kill Clark rather than letting him interfere further. Luckily, they forgot about Oliver, who pops up with an arrow in the shoulder for Plastique and Luthor's kryptonite ring for Parasite. Clark induces Parasite to return his powers to him rather than suffer the agony caused by the kryptonite, while Oliver spirits Tess to safety.
The next day, Clark asks Oliver where he got the ring. Oliver admits that he took it when he killed Lex. He hands over the black kryptonite and again urges Clark to kill Doomsday. Oliver claims that he and Clark are still on the same team, but Clark is pretty cranky. He zips back to the barn in Smallville, but can't find the crystal necessary to separate Davis from Doomsday. Tess appears and tells him that she destroyed it; Clark now has no choice but to kill the beast. She did so at the behest of a voice emanating from a Kryptonian sphere at Casa de Lex… claiming to be from the city of Kandor.
Oliver gets to be something other than bait this week, which is always a good thing. The episode plays with his moral gray areas rather deftly, while simultaneously allowing Tess to do her Machiavellian thing. The combo makes for a solid overall tone aptly cultivated by Welling (who steps into the director's chair here). The episode also plays up the mystery with Chloe reasonably well--we spend 40 minutes thinking she's come to her senses before realizing she's still out there with Davis somewhere--and Tess's little super-powered street gang makes a decent opening act for the big Doomsday showdown next week.
As befits any episode near the end of the season, a lot of plot threads come flying together very quickly. We get references to Kandor, the Black Creek supervillains, various Kryptonian goodies floating around Casa de Lex, and Oliver continuing to ride Clark about the whole "not killing anyone" thing. That results in too much expository dialogue--a regular problem with this show--along with a plethora of "shocking surprises" whose impact lessens with undue repetition.
Smallville also has a way of depowering Clark at the drop of a hat just to make sure he can't solve everything too quickly. It grows extremely tiresome, though using Parasite this time is an improvement over the usual surprise chunk of kryptonite. Oliver's various attempts to seduce Tess were pretty cheesy too--especially the second time while covering up his theft of the black kryptonite--though I suppose the ladies appreciate the odd bit of Justin Hartley beefcake once in a while.
On top of every other guest star the series has ever had, the Legion apparently returns next week to tell Clark all about his hideous ugly death.