Season 6 episode 6/20 "Noir"
Looks to be fairly cool.
IN A SPECIAL FILM NOIR EPISODE SHOT PARTIALLY IN BLACK AND WHITE, JIMMY SEES WHAT LIFE IN SMALLVILLE WOULD HAVE BEEN LIKE IN THE 1940s - After a secret meting with Lionel (John Glover), Lana (Kristin Kreuk) is shot at the Daily Planet by a mysterious gunman. Jimmy (Aaron Ashmore) is knocked out while studying photographs of the scene and dreams about a 1940s version of Smallville in which Lana is a femme fatale who orchestrated the murder of her tycoon husband Lex (Michael Rosenbaum), Clark (Tom Welling) works at the Daily Planet as a reporter and Lois (Erica Durance) is a sultry singer working at a bar owned by Lionel. Meanwhile, back in 2007, Clark discovers why Lana married Lex.