Catherine's (guest star Andrea Roth) plan to drive Andrew (Ioan Gruffudd) and Bridget, posing as Siobhan (Sarah Michelle Gellar), apart unravels. Agent Machado (Nestor Carbonell) discovers who wanted to kill Siobhan all along and rushes to intercept the killer before it is too late. Meanwhile, Siobhan's plan to help Henry (Kristoffer Polaha) backfires when the main witness suddenly dies.