Lionel Luthor: You know Clark's secret, don't you? I've been watching you since you've started seeing my son, and you've been getting closer and closer to finding out the shocking truth about Clark Kent. What a surprise it must have been to realize that Clark has kept up the deception for so long, right under your nose.
Lana Lang: He was trying to protect me. And he's not going to let you threaten me now.
Lionel Luthor: You think Clark's invincible. Not so. Like every hero, he has an Achilles' heel, a weakness. I know what it is. And Iknow that it could kill him.
Lana Lang: No. You could never hurt him.
Lionel Luthor: Would you bet Clark's life on that? I give you my word, Miss Lang, if you don't honor the promise that you made to my son or I find out that you have told anyone about this conversation, I will kill Clark Kent.
Read more Lana Lang Quotes
From: Smallville