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

as Chloe Sullivan

Annette O'Toole

as Martha Kent

Erica Durance

as Lois Lane

John Schneider

as Jonathan Kent

Kristin Kreuk

as Lana Lang

Michael Rosenbaum

as Lex Luthor

Tom Welling

as Clark Kent