Walter and Leo search for a missing man using a partial voicemail he left as a clue on The Finder. "The Conversation" is the 10th episode of the 1st season.
Added:

The Finder Season 1 Episode 10 Quotes

The reason I don't smack you is because I know you really want the answer.

Leo

Leo: You look like a vampire
Willa: Vampire's are hot
Walter: The world has turned. Vampires sparkle now.