Yesterday was Tom Welling's birthday and today is an all new episode of Smallville! Last week's episode was Truth. Lionel goes after Clark's secret! Here is the official preview from TheWB.com. Smallville #3-19 "Memoria" Believing that key information about his father's (John Glover) past was lost when his memory was erased, Lex (Michael Rosenbaum) decides to join an experimental program with Dr. Garner (guest star Martin Cummins) to regain the information so he can turn his father over to the FBI. Knowing that Lex will discover his secret if he regains his memory, Clark (Tom Welling) tries to stop him but is caught by Lionel and the doctor and exposed to the same radical treatment so that Lionel can solve the mystery of Clark's past. Kristin Kreuk, Allison Mack, Sam Jones III, Annette O'Toole and John Schneider also star. Miles Millar directed the episode written by Al Gough and Miles Millar.