During Castle's poker game, one of the players/writers is James Patterson (real-life author of several Alex Cross books) states that he wouldn't kill Alex Cross - main character of Along Came a Spider and Kiss the Girls (and books).
During Castle's poker game, one of the players/writers is James Patterson (real-life author of several Alex Cross books) states that he wouldn't kill Alex Cross - main character of Along Came a Spider and Kiss the Girls (and books)