A second meteor shower is headed for Smallville. Jor-El says that Clark must get all the Crystals. Lana may be wanted for murder. Lois is leaving to find her sister in Europe. Clark's graduation ceremony gets interrupted.
→ see also Category:Screencaps from episode 4x22
Lana returns to her apartment to find Genevieve Teague demanding Lana to give her the Crystal of Air. They fight until Countess Isobel transfers back into Lana's body. She stabs and kills Genevieve with the stone. The Mark of Transference disappears from Lana's back, because Isobel has finally gotten her revenge. Clark has a dream in which red, yellow, and blue lights come together to form a meteor. He is awakened by his parents, who say that Clark was yelling, "It's coming!" in his sleep. Meanwhile in outer space meteors start flying towards Earth.
Lex walks in immediately after Isobel kills Genevieve and convinces Lana that it was self-defense and she had no choice. He offers her one of the best defense attorneys in the nation. He tells her to stay in the Luthor Mansion and talk to no one until the lawyer arrives. Lionel goes to her apartment and takes the body. He threatens Lex that if he does not get the Stone from Lana by noon, Genevieve's body and evidence against Lana will be given to the sheriff.
Clark and Chloe notice that Lana is not at school to pick up her cap and gown. They start to worry when she misses the ceremony completely. Right after Clark receives his diploma, military vehicles pull up, interrupting the ceremony and announcing a meteor shower will hit Smallville in three hours. Clark urges Chloe and Lois to escape Smallville.
Lex offers Clark and his parents safe passage out on the LuthorCorp jet, but Clark rejects the offer. He goes to see Jor-El to ask him what he has done. Jor-El says that Clark has caused this himself because he did not collect the Stones of Power, and today he will witness the consequences for denying his heritage. He tells him that there is nothing that he can to do to prevent it from happening. Human blood has been spilled on one of the stones, causing a second meteor shower and a dark force from Krypton to come to Earth. If he does not unite the Stones at once, the Earth will be destroyed, and not even Clark will survive. The fate of the world is in his hands.
Clark returns to the Kent Farm where his parents are loading the car. He reluctantly tells them that he cannot go with them and he must unite the Stones. They are fearful because the last meteor shower was full of kryptonite and Clark could be killed. Sounding not very confident, Clark insists that he is the only one who can prevent the Earth's destruction. Finally, Jonathan states that all of Clark's trials have prepared him for this moment and tells Clark to go, and make them proud.
Clark finds Lana waiting for him in the barn. She gives him the Crystal of Air because she thinks that it is meant for him. They say they love each other and kiss, in case they never see each other again. She returns to the Luthor Mansion and leaves Chloe a short voice mail before Lex takes her phone and saying that she agreed not to contact anyone. When Lex asks Lana for the stone, she simply says it is safe.
Lois and Chloe are stuck in traffic, so they hatch a plan in which Lois distracts the guard at the roadblock long enough to let Chloe sneak by him to get to the Luthor Mansion and look for Lana.
Lex returns to the Mansion with Lionel waiting for him. They argue over the whereabouts of the Crystal of Water. When Clark sets the second stone in the altar, he hears a piercing sound which alerts him to the location of the final stone - in Lionel's pocket.
The stone emits a ray of energy, and Lionel is shocked into catatonia and Lex is knocked back against the wall. Unconcerned, Lex simply leaves his manservant to deal with Lionel after saying that he has become the son Lionel always wanted and puts the stone in his vault.
Clark superspeeds to the Mansion and flings open the vault, but it is full of kryptonite artifacts. He grabs the Stone right before he collapses.
As Lana boards the helicopter, Lex insists again that she give him the stone. She finally says she doesn't have it, angering him. Lana realizes that he is not interested in her safety and angrily boards the helicopter. Lex returns to the mansion.
Chloe finds Clark unconscious and drags him away. Lex walks in and finds Chloe, but Clark speeds out before Lex can see him. Lex demands Chloe to tell him why she is there and she insists that she does not know what happened. He drags her to the cave, demanding answers.
Jason ties Jonathan and Martha up and they try to fight back, but after a scuffle he manages to regain control.
The meteors hit all over Smallville. Lois is stuck in traffic and cannot get out before the meteors hit. She gets out of Chloe's car and escapes to higher ground. In tears, she watches as Smallville lays in ruins. The Kent house is hit by a meteor with Jason, Jonathan, and Martha inside it. During the showers, Clark Kent saves a boy named Henry at the last second, protecting the boy by using his body as a shield.
Lionel lies in a catatonic state at the mansion with Kryptonian symbols running in his brain. Lana's helicopter is hit by a meteor and crashes to the ground. Badly injured, she crawls to the edge of a crater containing a giant black spaceship.
Lex and Chloe see the light coming from the hidden chamber in the Kawatche Caves. Chloe pushes him against the cave wall from behind and he falls down, but she fails to knock him out. Clark combines all the Stones and the Crystal of Knowledge is created. Clark grabs the Crystal and is transported to the Arctic with Chloe unknowingly coming with him. He looks around the vast arctic landscape and in anger and confusion throws the Crystal.
- Darren Cooper
- Caroline Dreats
- Cody Davis
- Erica Feldman
- Lauren Felder
- Max Fromm
- Michael Hall
- Holly Harold
- Tanya Hart
- Kate Horton
- Michael Hoover
- Hannah Jacobs
- Michelle Jewel
- Clark Kent
- Lana Lang
- Chloe Sullivan
The following characters were established in later episodes, as having been part of the class of 2005:
- Susan Capra
- Suzanne Capra
- Gabriel Duncan
- Maddie Haroldhaus
- Tobias Rice
- Mark Verheiden
- Tom Welling as Clark Kent
- Kristin Kreuk as Lana Lang and Margaret Isobel Thoreaux
- Michael Rosenbaum as Lex Luthor
- Jensen Ackles as Jason Teague
- Allison Mack as Chloe Sullivan
- John Glover as Lionel Luthor
- Annette O'Toole as Martha Kent
- John Schneider as Jonathan Kent
Special Guest Star
Special Appearance by
- Anthony Harrison as Head Astronomer
- David Orth as Soldier with Microphone
- Tom Pickett as Terrence Reynolds
- Craig Veroni as Minion
- Robert Gavin as Helicopter Pilot
- Jeremy Jones as Young Father
- Kwes Thompson as Soldier at Roadblock
- Brayden as Henry
- "Pomp & Circumstance" - Edward Elgar
- Commencement means to have begun. It is also another word for a high school graduation ceremony.
- Clark and his friends graduate this season from Smallville High.
- The title could also refer to Clark starting on his journey towards his destiny by creating the Crystal of Knowledge and with it, the Fortress of Solitude.
- Antagonist: Jason and Genevieve Teague
- This is the season 4 finale.
- This is the 2nd season that finishes with the credit "To be continued". Other episodes which culminate with this expression are: Tempest, Calling, Exile, Oracle, Vessel, Phantom and Salvation.
- Clark uses the following abilities in this episode: super strength, super speed, and invulnerability.
- One of the graduates mentioned at the ceremony is "Holly Harold", who has written nine episodes of Smallville. Another graduate is called "Caroline Dries". She was also a member of the Smallville production team.
- This is also the last episode with the old style of the Opening credits.
- A repeat of this episode on Season 4 DVD during mid-afternoon cut the scene with Jason Teague kidnapping the Kents. 
- When this episode aired in Australia, Clark's dream sequence at the start was removed and instead attached to the end of the previous episode Forever. This was most probably due to Network Ten's tight schedule in airing the extra-long episode. Also, much of the scenes with Jason and the Kents fighting in the house were cut.
- When this episode aired in the UK, it was cut to fit the usual one-hour time slot (including commercials). The entire event where Jason captured and threatened Jonathan and Martha at their farm was deleted. 
- The timer is at 45 minutes as the meteors strike the atmosphere, while in real life the process of passing through the atmosphere usually takes only seconds.
- When the heroes are discussing the need to go look for Lana, Clark's shirt switches between wet from rain (in medium shots) and dry (in close-ups).
- Lois mentions she can’t spell, a trait her comic and film counterparts also share.
- It is curious how Lois can punch Clark so hard in his arm and yet not feel hurt by his indestructible body.
In Other Media
- This episode contains several Superman allusions: Lois tells the Kents she had a nightmare about a "guy wearing a red cape", jokingly tells Clark that he will "go into the big city and make his mark", and then rejects the possibility of her becoming a journalist on the grounds that she'd end up opposite "the most bumbling reporter on the masthead" (a reference to Superman's 'mild-mannered' alter ego in the comics).
- In Clark's premonition, he sees red, yellow, and blue lights in the sky, Superman's colors. Also, the crystal takes the shape of the Kryptonian pentagon on Superman's chest and their glow is of the color, red, blue, and yellow; and when Clark woke up from his dream, he had a red blanket draped around him, Martha was wearing a yellow robe, and Jonathan was wearing blue, all Superman colors.
- The ending scene is very similar to how in Superman: The Movie a young Clark throws the kryptonian crystal into the arctic, where it forms his Fortress of Solitude.
- On its original airing, this episode filled a 90 minute time slot with the last ten minutes featuring an exclusive 10-minute preview of the movie Batman Begins. The episode itself is about ten minutes longer than others.
- According to the message from Alfred Gough & Miles Millar in the Season 4 DVD booklet, this was the most expensive episode since the Pilot.
- This is the last appearance of Jensen Ackles as Jason Teague. It was his first and last season. It is also the last appearance of Jane Seymour as Genevieve Teague.
- This episode received the 2005 Emmy nomination for Outstanding Sound Editing For A Series.
- This is the last episode that Erica Durance (Lois Lane) is credited as a "Special Guest Star".
- The astronomer at the research facility that spots the asteroid is reading Adbusters - a popular sub-culture magazine.
- The theme playing when they graduate is "The Pomp and Circumstance Marches" (full title "Pomp and Circumstance Military Marches"), Op. 39, a series of marches for orchestra composed by Sir Edward Elgar.
- John Glover makes his 50th appearance as Lionel Luthor in this episode.
- Scenes from Clark's vision of a meteor shower in the epsoide Scare are used in this episode.
- Clark had a precognitive hallucination about a second meteor shower in Scare when infected with a fear toxin.
- Clark comes across the mask with kryptonite eyes in Lex's vault. The mask was last seen in China in Sacred.
- Shelby was last seen in Spirit.
- This episode marks the 24th appearance of Clark's red jacket & blue shirt outfit, which he wears frequently throughout the series. It also marks the second time that Clark wears his Red jacket/Blue shirt outfit in a season finale. He previously wore this outfit in the Season Three finale, Covenant.
- Interestingly, this episode bears some similarities to Season One's Tempest, in that Lionel is injured in some way and Lex has a choice of taking him or leaving Lionel to die in an impending disaster that will hit Smallville, although this time Lex chooses to leave his father for dead.
- When Lionel is rendered unconscious by the stone, he has actually discovered Clark's secret, although this isn't revealed until the season five episode Cyborg. (Lionel comes clean to Clark in Mercy).
- Chloe, Clark, Lex, Lionel, Lois, Lana, Martha, Jonathan and eventually Jason's fates are revealed in the next episode.
- Lex reveals two years later in Wrath that the date of the second meteor shower is May 18, 2005, the day that this episode originally aired.
- Lois: Clark, I know how devastated you must be but if you could just keep the tears to a minimum, I'd appreciate it.
- Clark: I'll try.
- Lionel: You know, for a woman without a heart, Genevieve Teague certainly did have a lot of blood.
- Lex: Can you hear me, dad? Before you leave this Earth, I want you to know... you did create the son you always wanted.
- Jason: I'm having what you'd call a rough day.
- Lois: You know, I took this career test in some magazine- it said that my perfect job would be a radio disc jockey.
- Clark: That would make sense- you talk enough. There won't be any dead air.
- Clark: Journalism, ever thought about that? You wrote some half decent articles at your short lived career at the Torch.
- Lois: Kill me first. Even if I could spell, the last thing I would do is spend my time in a newsroom. With my luck, I probably end up across the desk of the most bumbling reporter on the masthead.
- Chloe: Because you have a way of getting things done in half the time a normal person gets things done.
- Clark: And I'm not normal?
- Chloe: No, of course you're normal, Clark. You're as normal as they come
- Clark: If you are my father, talk to me. Tell me what you've done!
- Jor-El: It is you who has brought this upon yourself, Kal-El.
- Clark: What did I do?
- Jor-El: I sent you here to unite the three elements.
- Clark: The stones? They have nothing to do with me.
- Jor-El: But they do, Kal-El. For the knowledge of the universe is meant for you only. Yet you chose to deny your heritage. Today you will witness the consequences.
- Clark: So you send a meteor shower.
- Jor-El: I have done nothing, Kal-El. Human blood has stained one of the elements and awakened a great danger from the darkness of space.
- Clark: What can I do to stop it?
- Jor-El: There is nothing you can do to prevent what is already in motion. But the meteor shower is just the beginning, Kal-El. I warned you that the elements could not fall into the hands of a human. The three must become one. It is the only way to save Earth from total annihilation.
- Clark: I don't know where they are! I don't have time to find them!
- Jor-El: If you don't unite them at once then you, my son, will be seared by a fire from the sky even you can't survive. The future of mankind rests in your hands, Kal-El.
- Clark: Please help me! I can't do this alone!
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