Smallville :

After Lana is visited by the ghost of her childhood friend, she turns to Clark for help in uncovering the truth about the strange visitor. However, Clark realizes that the little girl is actually a kryptonite-enhanced clone, and he rushes to save Lana before the revenge-seeking child harms her.

Meanwhile, Lex, who is preparing for his wedding to Helen learns that Lionel is funding the cloning research.