Visitor

S2 E18: After his schoolmate, Cyrus Krupp (Jeremy Lelliott), claims to be an alien and seemingly proves it by using heat vision, Clark investigates and begins to believe that the boy is from Clark's home planet, Krypton. Meanwhile, when Helen (recurring guest star Emanuelle Vaugier) discovers a locked room in the Luthor mansion, she demands to know what is inside -- and Lex must decide whether or not to admit the truth about his ongoing investigation of Clark.