When Castle appears on a late-night talk show to promote his book, Heat Wave, legendary host Bobby Mann leans in during a commercial break and whispers, "they want me dead." When Mann dies later that night, seemingly of natural causes, Castle has to convince Beckett that there was foul play. During the investigation, Castle is seduced by a Hollywood hottie, who was the other guest on Bobby Mann's show the night he died.

A fight between Leonard and Penny threatens their relationship, while Sheldon battles Wil Wheaton in bowling.

Tonight Stephen welcomes the founder of Wikileaks, Julian Assange. Also, Stephen talks with Jeffrey Toobin about the replacement of Supreme Court Justice John Paul Stevens.

From Project Runway, Tim Gunn; and actress Kathy Kinney

Murder: Father Reynaldo Rivera Lost: Laurence Harding Jr. Wanted: Kathy Powers Mystery: Qi Gong Update: Lost: Matthew Chase Lost: The Friend of Moises Treves

Mystery: Luis Diaz Murder: Jordan Children Lost: The Children of Georgia Tann Lost: Frank Bloomer