20. The Late Shaft

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.