Lois' younger sister, Lucy (Peyton List), with whom Lois doesn't get along, visits Smallville and charms everyone she meets. However, Clark discovers a darker side to Lucy after he catches her stealing money from a bar. Clark forces Lucy to reveal the truth about her sudden appearance in town -- a truth that puts Lois in grave danger. Meanwhile, the crystal disappears from Lana's apartment, and Jason accuses Lionel of stealing it.

Season 4 | Episode 16

Allison Mack

Chloe Sullivan

Annette O'Toole

Martha Kent

Erica Durance

Lois Lane

John Schneider

Jonathan Kent

Kristin Kreuk

Lana Lang

Michael Rosenbaum

Lex Luthor

Tom Welling

Clark Kent