In Smallville’s fifth-season finale, Clark’s kryptonian origins threaten the Earth and the population, which Clark must make a huge sacrifice and a decision. This decision will affect all of the citizens around him, affecting Lex, Lionel, Lana and Clark are set in motion, in the moment for which all his trials have prepared him for. Meanwhile Milton Fine unleashes a deadly virus that effects millions, and Lionel is again channeled by Jor-El who helps Clark (Kal-El) in the on sought battle between good and evil.

Clark and Martha are both visited by Jonathan’s ghost, who warns them about Lionel and claims that Clark must kill him to stop him. Meanwhile, Fine will do whatever it takes to get the vaccine from Lex.

Clark saves a man who in gratitude decides to help Clark in return…by using his ability to turn invisible and his skill as a hitman to kill Lex so Clark can reunite with Lana. And Clark and Lana finally square off about Lana’s new relationship.

Lionel is taken hostage by a masked man who forces him to play elaborate games for the prize of staying alive. Martha goes to confront Lionel after Clark tells her Lionel knows his secret and becomes a part of the game herself, fighting for her life.

Clark befriends a little girl who has the ability to telekinetically shatter glass, then comes to her aid when it’s believed she killed her mother in a brutal stabbing attack. Meanwhile Lex and Lana grow closer together and Chloe finds out about it.

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.

Clark is hypnotized by a woman who uses a supposedly magical charm to control others – he reveals his super powers and is sent to kill Lex. Meanwhile, Lex has tracked down the missing Professor Fine and plans to confront him, unaware that Clark is coming to murder him.

Clark finds himself up against Lex when he befriends Victor Stone, a half-machine, half-human subject who escapes from LuthorCorp with the aid of a sympathetic doctor.

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.

Clark discovers that the new assistant at the Daily Planet, a bespectacled, bumbling woman named Andrea, is actually a mysterious female vigilante who stalks Suicide Slum. Her path crosses Clark’s as they both seek the same criminal. Meanwhile, Clark’s bottled-up grief threatens to get the best of him and LuthorCorp experiences a shakeup.