Having seen him in Firefly / Serenity, Slither and some other movies over the years, I must admit that I immediately gravitate to any TV show or movie that stars Nathan Fillion.  The TV show just starting its second season, Castle, is no different: Fillion plays a detective-story author living in New York who works his contacts to work hand-in-hand with an NYCPD detective on various cases while he uses the "experience" as research material for his new books.