Superman's teen years as Clark Kent find him agonizing over his shy, uncertain persona while dealing with his evolving powers and an infatuation with classmate Lana Lang.
Chloe invites an injured 15-year-old to move in with her. Meanwhile, Clark experiences his first day of work with Lois.
Lana and Lionel have a secret meeting, after which Lana is shot. While Jimmy is observing photos of the encounter, he is knocked unconscious. While unconscious Jimmy dreams about what life in Smallville would have been like in the 1940s. Clark is a reporter at the Daily Planet, Lana is a siren who planned the demise of her magnate husband Lex, and Lois is a singer at a bar that Lionel owns.
Tess invites Clark to a press conference in New York but when an explosion rocks the private jet they are on, Clark must figure out how to save them without Tess learning his secret. Unbeknown to Clark, Tess orchestrated the explosion to get Clark to reveal his powers. Meanwhile, Davis discovers a surprising way to control the monster within.
Lex tracks the amnesiac Kara to Detroit, where Lois follows him. An obsessive busboy infatuated with Kara shoots Lex, and Chloe has to determine whether to heal him or not.
Lana joins a sorority to get housing for her last-minute college registration, but the sisters have a deadly agenda which involves turning Lana into a vampire like themselves and sending her against Clark. Meanwhile, Chloe applies to become an intern at the Daily Planet and runs up against the editor-in-chief, Pauline Kahn.
Linda Lake returns to Metropolis and threatens to expose Clark’s secret unless he promises to give her exclusive information on the red-blue blur so she can become a star reporter again. Refusing to be blackmailed, Clark tells Lois his secret and asks her to write his story for The Daily Planet.
Chloe returns and begs Clark to kill Davis, claiming he can no longer keep the beast under control. Tess has assembled a team of meteor freaks, including Plastique, to track down Davis so Clark can kill him. However, things get out of hand once Tess’ team discovers she is double-crossing them.
Clark and Lois head out of town for a quiet romantic getaway, but their plans are thwarted when they run into Chloe and Oliver at their Bed & Breakfast Inn. The couples' awkward moment is interrupted by the arrival of the Silver Banshee, who sets her sights on Clark and Oliver. Meanwhile, Tess faces off with Zod with a surprising result.
Clark learns that John Jones was shot while working as a police officer; Lana tells Tess that Lex isn't the man she thinks he is, forcing Tess to re-evaluate her position as head of Luthercorp.
When Oliver is poisoned, he starts having flashbacks to the period when he gained his archery skills... and met Tess. Meanwhile, Chloe has to make a decision which surprises Clark.
Zod and his soldiers release a virus into the air that turns humans into zombies. The only way to stop it is to make an antidote from the blood of another Kryptonian. After Lois is infected, Chloe pleads with Clark to donate his blood to stop the epidemic, even though it risks outing him to Zod.
Oliver's past comes back to haunt him in the form of The Dark Archer, Oliver's former teacher, who seeks revenge on his student by taking aim at Lois and Chloe. Oliver faces down The Dark Archer after his former mentor kidnaps Mia AKA "Speedy" but is pushed to his limit and Clark races to stop him from making another deadly mistake.
Oliver is drugged and kidnapped by a woman named Victoria AKA Roulette, who tells Oliver that he’s involved in a dangerous game and must fight for his life. After Victoria shows up dead and Oliver is arrested by the police, he turns to Chloe for help. Meanwhile, Lois berates Clark for not telling her about Oliver's suicide attempt.
Clark discovers that Davis is still alive and confronts Chloe about protecting him. Oliver discovers Jimmy breaking into Chloe’s apartment, but things get rapidly worse after Davis jumps from the shadows and attacks both of them.
Chloe begins to notice that Clark's not acting like himself. Bizarro enlists the help of Brainiac.
Clark is in his barn one moment... and the next finds himself in a psychiatric hospital where he discovers he's been suffering from delusions that he came from another planet and has super-powers.
A mysterious man who claims to be a product of Lex's latest project plants a bomb on Chloe and uses her to force Lois to get the truth from Lex.
Lucy Lane, Lois' younger sister, comes to Smallville but Clark catches her stealing money from the Talon to pay off a European crime syndicate. Lex offers to help but everything is not what it seems. Meanwhile, a thief breaks into Lana's apartment and steals the crystal, and Jason suspects Lionel.
Oliver tells Clark he must kill Davis, as Doomsday is a serious threat and must be stopped at all costs. However, Clark struggles with taking a human life, so the Green Arrow and his team decide to take matters into their own hands. Lois takes on Tess, but the fight takes a shocking turn. Meanwhile, Chloe gets caught in the middle of Oliver and Clark’s battle over killing Davis.
Chloe is possessed by the spirit of a young girl whose body is sealed in the Talon's walls, and goes searching for the girl's killer while Clark and Lois try to track her down.
Distraught over her break-up with Clark, Lana goes to a rogue medical student who experiments with a dangerous kryptonite-based serum that allows people to flat-line but see their dead loved ones. Lana attempts to see her dead parents using the serum and when Clark returns from Honduras to help her, the doctor injects him with the serum and Clark speaks with his dead father...who warns him that Lionel knows his secret. Meanwhile, Lionel continues working to get closer to Martha, and Lex has a near-death vision of his mother.
While his father is awaiting surgery, Clark befriends a young boy, Garrett whose brother Vince just died from liver failure. However, everyone is shocked when Vince shows up alive and seemingly well - until his liver starts failing again. In a desperate attempt to keep his brother alive, Garrett straps a Kryptonite bomb to himself and demands that Vince be given Jonathan's liver or he will blow up the building.
While Clark seeks out Brainiac to force him to fulfill his side of their bargain and restore Lana, Chloe and Jimmy go up against the government.
Jor-El mysteriously arrives at the Kent farm searching for his son, Kal-El, but meets Chloe instead. Convinced the Blur is Jor-El, Zod enlists Tess’s help in finding him to force him to reveal the secret to his powers. Clark realizes Jor-El is alive and on Earth and races to find him before Zod does.