Smallville - Season 4 - Eps 19: Blank
When a boy who can make people lose their memories robs the Talon, Clark goes after him but gets total amnesia. Chloe finds out what happened and has to tutor Clark in the use of his superpowers and make sure he doesn't accidentally reveal his secret. While Clark, Chloe, and Lois try to track down Kevin, Clark takes advantage of his "new life" to ask Lana on a date. And Lex tries to turn Clark's memory loss to his advantage by getting him to reveal the secret of the caves.
About Smallville

Title: Smallville
First Air Date: 2001-10-16
Last Air Date: 2011-05-13
Status: Ended
Rating: 8.2/10 (from 4151 votes)
Language: EN
Seasons: 11
Total Episodes: 216
Network: The WB The CW
Genres: Sci-Fi & Fantasy, Action & Adventure, Drama
Production Companies: DC, Warner Bros. Television, Tollin/Robbins Productions, Millar Gough Ink
Synopsis
The origins of the world’s greatest hero–from Krypton refugee Kal-el’s arrival on Earth through his tumultuous teen years to Clark Kent’s final steps toward embracing his destiny as the Man of Steel.
Cast

Tom Welling
Clark Kent

Erica Durance
Lois Lane

Cassidy Freeman
Tess Mercer

Justin Hartley
Oliver Queen