During Clark's battle with the last Phantom Zone wraith, Lex is rescued by a mysterious woman. She then goes to the Kent farm and reveals she is Clark's cousin, Kara, from Krypton.

Kara takes to life in Smallville by getting a job at the Talon, and entering the Miss Sweet Corn Pageant as a contestant, overruling Clark's objections. However, Lex takes an interest in her and three of the other contestants discover she has super-powers and decide to use her to steal a valuable time capsule.

Kara goes to Washington to look for her missing crystal, but is captured after she breaks into the lab. She's sedated with a truth serum that has kryptonite in it, which makes her relive a trip to Earth from the past. In this past trip she followed Lara, Clark's biological mother, to the Kent's farm. Clark saves Kara, but also ends up being affected by the serum when he burns it with his heat vision.

Lana absorbs Clark's powers during a lightning storm, which she uses to break into Lex's safe and steal some incriminating evidence. After being turned away by Grant at the Daily Planet, who won't accept her stolen evidence, Lana goes after Lex herself. Clark tries to rescue Lex, but must first battle the super-powered Lana.

Chloe begins to notice that Clark's not acting like himself. Bizarro enlists the help of Brainiac.

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.

Lionel has Clark kidnapped, and when Chloe and Lana confront him, he makes them think Lex is the culprit. Chloe and Lana then beg Jor-El to restore Kara's memory because she's the only person who can rescue Clark.

Clark must learn a new superpower as he and Kara join forces to take on Brainiac, putting the lives of their friends in danger.

No one is safe when Lex seeks the secret of Veritas, and Clark tries to stop him.

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.

When Clark wonders if the world would be better off if he never came to Smallville, Jor-El shows him what life would have been like if he had never existed.

Lex is taken to the Fortress to fulfill his destiny, while Lana awakens from her coma and Chloe is arrested by the government.