HAROLD AND KUMAR GO TO WHITE CASTLE star Kal Penn is joining the cast of the hit series 24. Penn will play a man involved with the leader of a neighbourhood mosque. Although the US Fox network will not reveal plot details, Penn is thought to be the key to a terrorist plot. The sixth season of the show starring Kiefer Sutherland, will premiere in January (07) and picks up 20 months after last season's finale.