Clark (Tom Welling) is stunned when he sees his father's ghost (John Schneider) at the graveyard, but becomes even more confused after Jonathan tells him he must kill Lionel (John Glover). Meanwhile, Lex (Michael Rosenbaum) develops a vaccine for Fine's (guest star James Marsters) deadly virus, but Fine intervenes and injects him with the vaccine, which causes a shocking reaction in Lex.