Zod continues to pose as "The Blur" and asks Lois to investigate one of Tess' secret labs. An explosion rocks the lab, and Lois is rescued by John Corben who was a subject of multiple experiments. While investigating the explosion, Clark is exposed to red kryptonite. An infected Clark takes Zod to the Fortress. Tess turns to Chloe for help and they send in Corben to stop Clark from revealing all his secrets.
→ see also Category:Screencaps from episode 9x17
Lois is digging up information on Tess Mercer in one of her labs just like "The Blur" (aka Zod) asked her to do. She finds out that Tess' scientists are performing many experiments with kryptonite, but she doesn't know on what. When Lois attempts to find out, a security guard and one of the scientists discover her and they try to get her to leave. As Lois is being hauled off, the scientists discover that their experiment has gone missing. In the commotion of finding whatever it was that went missing, Lois is able to knock out the security guard and attempt to escape. However, an explosion knocks her unconscious and she is rescued by someone with a green and glowing heart.
The next morning, Clark goes to visit Lois. She has an unexplained cut and can't seem to remember how she got into bed with the clothes she was wearing the night before. Clark becomes convinced that Lois is hiding something from him. As Lois tries to distract him from asking more questions "The Blur" (still Zod) calls. Lois excuses herself from Clark, to inform "The Blur" about Tess' labs, but assumes that he already knows about them because she thinks he saved her in the explosion. Lois hangs up on him to go find Clark and apologize, when she stumbles upon John Corben in an old warehouse. It is there that Lois learns about John's upgrade, a small device they've inserted on his neck to control his every move. She also discovers that John saved her and that unless he finds kyrptonite and fast, his heart will stop. Wanting to help him, Lois helps Corben to her car so they can search for kryptonite.
In the meantime, Clark wants to know what Lois has been hiding from him, so, with Chloe's help, he tracks where she went last night and ends up in a random spot on the street. He notices a manhole right by where he's standing. Clark ends up where Lois was the previous night as a great deal of red smoke surrounds him - it's red kryptonite.
Clark heads back to Watchtower and when Chloe arrives she sees that he's discovered that there are arsenals of kryptonite all over North America. Convinced that this is Tess' doing, Clark is about to head out to confront her, but Chloe stops him and tells him that the arsenals are hers. Chloe tries to explain that they were in case of an emergency, such as the Kandorians attacking Earth, but Clark becomes angry that she didn't tell him and knocks her to the ground. He burns a huge Mark of El on one of Watchtower's walls before taking off.
Meanwhile, John has discovered one of Chloe's arsenals and uses some of the kryptonite bottles to refuel his heart. As he starts to get out of the truck, Clark arrives and is weakened by John's heart. Zod flies in and arrives right afterwards, blows up the truck, gives Clark a little nod, and leaves. Lois arrives on the scene not too long afterwards to see if John is all right. He tells her that The Blur blew up the truck. Lois is skeptical about John's claims however she does remind him that the last time he encountered The Blur, John attacked her and tried to kill her. Lois believes if the Blur really did attack him it wasn't intentional.
Chloe arrives at the underground lab and finds Tess. She notes that Tess is still a wanted fugitive on Checkmate's radar, and Tess deduces that Clark must have turned against Chloe after he discovered her kryptonite arsenal depository. While searching through the wreckage in the lab Chloe discovers traces of red kryptonite in the lab, accounting for Clark's irrational behavior. Tess learns that Red kryptonite changes Clark's personality from a good old wholesome farmboy to a rebellious and immoral bad boy. Tess reveals to Chloe that she had her scientists conduct experiments with both the Green and Red Kryptonite to upgrade her new bodyguard. Chloe warns that if Clark reveals the existence of the Kandorians to the world, Tess' goals are in jeopardy.
Elsewhere at a warehouse, Zod is experimenting with a lead-covered kryptonite dagger and discovers it's the source of weakness that causes him pain, so he immediately covers up the weapon with the lead sheath. Just then Clark appears behind him. Zod begins to explain the irony to Clark about how a piece of their home planet has become their own Achilles heel on earth. Clark inquires how he acquired his powers . Zod informs him that he gained access to his Kryptonian abilities from the blood that Clark had provided to him. Zod then begins to play upon the isolated emotions Clark must have felt growing up, being the only one of his kind. Zod says that none of Clark's friends could possibly truly understand him, and that he needs an equal. Clark insists he has no equal but when Zod says that by joining force they could accomplish much together as brothers, Clark under the influence of red kryptonite reconsiders his offer with a gesture of a Kryptonian handshake.
John and Lois board a bus heading for an army base in South Dakota where her father General Lane has a doctor Emmet Vale waiting to help John. John sees a woman struggling to get her luggage into the rack but when he helps her she slips a green disk onto the back of his neck where his input upgrade was installed. It immediately commands him to return to base and John and the woman exit the vehicle with Lois being cut off by another of Tess' agents and injected with a needle which knocks her out. Lois is left on the bus as John and the agents walk away.
Zod and Clark are walking away from a green kryptonite cache they've just set ablaze. Zod is intrigued by Clark's sudden enthusiasm in seeking retribution. Zod also points out how Clark reminds him of his father Jor-El and how during their friendship, even when they used to fight, he still admired and respected him. He assures Clark that he now has someone who's like a brother that truly understands him. Together they head to the top of the Space Needle structure in Seattle. As they look out across the city Zod continues to talk about the relationship he had with Jor-El. Clark offers to take Zod to the Fortress where he can talk to his old friend. But just before that Clark decides to have a little fun with his powers by creating a snowy blizzard in Seattle with his Arctic breath.
Back in Tess's lab, Chloe detects an unusual weather disturbance emanating from Seattle. She uses satellite imagery to see that Clark and Zod are responsible while they are atop the space needle. Chloe notices Tess' reaction towards Zod having his super powers and realizes that she's known about his recent power recovery. Tess doesn't respond but she does admit that she's confused as to Clark and Zod's sudden alliance. Before Chloe can explain any further they're interrupted by the arrival of John Corben, who is now a mindless drone due to the chip interface in his neck.
Arriving at the Fortress of Solitude, Clark gives Zod a brief tour while also explaining the purpose of Jor-El's A.I. program, which is accessible from the crystal console. But it appears to not be functioning properly due to Zod's presence. Clark tries to manually rearrange the crystals but to no avail as the console still doesn't operate as it should. Furious with Jor-El refusing to respond, Clark threatens to destroy the fortress. But Zod convinces him not to proceed, reminding him that his father left the book of Rao on the planet somewhere, and with that book's knowledge and the fortresses' technology there would be no limits to what they could achieve. Clark agrees with a smile.
Chloe tracks Corben's location but as he approaches the designated destination, she switches off the computer monitor just as Tess approaches and asks where Chloe sent Corben. Chloe pretends it's just a hunch and refuses to provide any more detail. Suddenly they both hear a noise coming from the entrance of the lab. Chloe goes to investigate. Lois comes in to confront Tess and insists that Tess can't cover up what she's done to John Corben or this secret lab beneath Metropolis. Chloe appears behind Lois using chloroform to knock her unconscious and tells Tess she'll take care of her cousin while Tess cleans up any evidence of the laboratory existence to make sure no one ever believes Lois's story.
Corben arrives inside the Fortress using the portal entrance from the Kawatche Caves and uses his kryptonite heart against them. Zod and Clark try to outflank him as they start to weaken from the kryptonite radiation. Clark uses his heat vision to bring down the ceiling on him attempting to crush him flat. But the impact instead knocks loose the control chip. Corben begins to advance towards them, now back in control of his will. Zod and Clark combine their superbreath to freeze Corben in place in an ice crystal.
However, Corben's kryptonite heart powers up, giving him the strength to break free. Corben kicks Zod aside and turns his attention to Clark, and begins to explain that someone sent him there to save Clark. He then uses a shard piece of kryptonite to stab Clark, which frees him from the effects of red kryptonite. Corben then picks up the control chip and uses the Key to teleport himself out. Clark looks around and realizes that Zod is long gone.
Later, John meets Lois on the street in Metropolis, where she gives him the new red kryptonite heart she'd retrieved from the lab. John expresses his admiration for her honesty and loyalty towards him, and the fact she gave him a second chance when no one else would have. He wonders if she'd want to pursue a meaningful relationship with him. Lois admits that she's grown to like him as a friend but she's with someone else right now who's very important and special to her. Corben says she's a real dame and hopes the guy she's with knows just how lucky he really is.
Elsewhere, Zod is drinking when Tess arrives and confronts him with photos of himself with Clark atop the Space Needle structure. She warns him that she's the only one who has Zod's best interests at heart, as long as she benefits from it as well. When he points out Tess is the one who sent Corben to attack him, Tess notes that he hasn't… yet. They then kiss passionately, and Tess warns Zod that Clark isn't as reliable as he may think. She then shows Zod the photos of Clark providing Faora and Alia human ID papers and claims that Clark is slowly forming a rebellion alliance against him with his own people.
Inside Watchtower, Chloe is cleaning off the House of El signature that Clark had previously burned into the wall. Clark arrives to apologize to her, admitting that in that future he had witnessed prior to its alteration, Chloe's kryptonite arsenal was the only thing that helped humanity have a fighting chance against the Kandorians. Clark admits that the red kryptonite unleashed his innermost desire to have a family and a feeling of acceptance that he longed for, and that in a strange way Zod represented the closest thing to an actual family he could have.
Unbeknownst to Clark however, Zod assembles the remaining loyal soldiers at the Fortress and uses the kryptonite-laced knife to cut himself with as he gives a speech to his followers about accepting their birthright. He drips the resulting blood into a bowl and tells them that they will prevail, and offers the blood to them so they can also access their natural Kryptonian powers that are rightfully theirs to claim.
- Tom Welling as Clark Kent
- Allison Mack as Chloe Sullivan
- Erica Durance as Lois Lane
- Cassidy Freeman as Tess Mercer
- Callum Blue as Zod
- Justin Hartley as Oliver Queen (credit only)
Special Guest Star
- Paul Jarrett as Scientist
- Dean Redman as Lab Guard
- Alex Stevens as Female Agent
- Guy Christie as Male Agent
- The term "upgrade" refers to the replacement of a product with a newer version of the same product. It is most often used in computing and consumer electronics, generally meaning a replacement of hardware, software or firmware with a newer or better version.
- The title refers to John Corben's "upgrade" that was made on him by Tess Mercer's scientists.
- It also refers to Zod upgrading his Kandorian soldiers by using his own blood to give them their powers.
- Brian Austin Green revealed that an alternate ending was filmed for this episode in which John, while wearing the Red Kryptonite heart, voluntarily chose to reactivate the chip and become devoid of emotion following Lois’ rejection. Green also revealed he initially decline to reprise the role due to the fact the script wasn’t completed at the time of the offer. He expressed dissatisfaction with the final product, while also expressing a willingness and desire to return to the series in the final season. While Corben did appear in Prophecy, Green did not return and body double was used in his place. 
- Green later speculated that his unfavorable remarks on the episode were responsible for his not being invited back for the final season. 
- Antagonist: Kal and Major Zod
- Oliver Queen does not appear in this episode.
- Lex Luthor and Sam Lane are referenced in this episode.
- This is Major Zod's first visit to the Fortress of Solitude.
- This is the sixth and final time that Clark is infected by red kryptonite: the first one was in Red; the second one in Rush; the third time happened during Exodus, Exile, and Phoenix; the fourth time happened in Unsafe; and the fifth time happens in Crimson.
- This is the first time Professor Vale is mentioned. Here, Lois refers to him as Dr. Vale.
- This episode marks the introduction of the arctic version of super breath as one of Clark's powers, although Clark used his superbreath to cool down Lois' coffee in Rabid.
- The music in the scene when Clark and Lois are in the Talon is the same music that plays at the beginning of Metallo.
- John Corben uses the key to enter and leave the Fortress which was last seen and used by Chloe and Davis in Beast.
- The Daily Planet is not featured or shown in this episode.
- This is the second time that the three lead females (Chloe, Lois and Tess) all appear together in a scene. The first time was in the alternate future in Pandora, when Tess was killed by Chloe.
- When Clark is talking with Chloe in Watchtower he bumps into the table as he walks away.
- This is the third time Clark has been affected by kryptonite in form of dust. The first was in Fever with Green kryptonite, and the second was in Persuasion with Gemstone kryptonite.
- When Lois is walking down the stairs to the basement of the Talon, there is a glimpse of a poster reading "It's All Downhill From Here". This could be referring to fact that this is the return of John.
- John Corben appears for the first time in Savior and was defeated by Clark in Metallo, where he lost his kryptonite heart and it was found by Tess Mercer.
- Tess gave the kryptonite heart to Toyman in Echo, and ordered him to figure out how it works.
- In Conspiracy, it was mentioned that Corben's body was the only one not recovered by the morgue after being stolen by the Kandorians.
- The Fortress of Solitude was last seen in Echo.
- Red kryptonite was last seen in Crimson.
- This episode marks the 15th appearance of Clark's "black" Blur outfit, which he wears frequently throughout Season Nine (except for Kandor, Society and Escape) and in the Season Ten premiere Lazarus. He previously wore this outfit in Savior, Metallo, Rabid, Echo, Roulette, Crossfire, Idol, Pandora, Disciple, Absolute Justice, Part 2, Warrior, Persuasion, Conspiracy and Checkmate.
- The Kandorian army was last seen in Persuasion.
- Chloe: Clark Kent at the keyboard? Have I been downsized in the bureaucratic world of superheroes?
- Kal: I just got tired waiting for you.
- Chloe: Oh, snap. Someone woke up on the wrong side of the planet.
- Kal: More like the wrong side of Lois. But that will never happen again.
- Kal: God, I was such a fool to think that you could ever understand me. You think you're better than Tess. At least she didn't pretend to be on my side all those years.
- Chloe: Clark, why don't you hear my side? I mean, what if some day there was a war?
- Kal: There is a war, Chloe. Right now. And you're about to lose it.
- Chloe: I should have known that Clark took a walk down the ruby-red road. That explains his lack of "edit" button.
- Tess: I thought Clark was only affected by green meteor. What's the red do?
- Chloe: Basically it turns him into the bad boy every girl dreams of... in her nightmares.
- Chloe: Guess who's coming for dinner, together... with powers. But you already knew that, didn't you?
- Tess: What I don't know is why the sudden bromance.
- Lois: Tess. How not surprised am I to see you here. By the way, this is the least-secret secret lab I've ever been in... twice.
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