The Basics: Rick Castle is millionaire playboy author by day and a police-consultant (barely) by... well, day. He shadows NYPD Dets. Beckett, Esposito and Ryan, often helping them solve most of their cases and uses Det. Kate Beckett as his inspiration for his character Nikki Heat. After 4 years, Kate and Rick finally got together and we see their relationship taken to a new level, though one filled with some doubt on Beckett's part. Rick's daughter, Alexis, also saw less screen time and some growth for her character as she started university last season. The Turn Up: Who doesn't like a good bad guy? It seems a slightly larger story arc is at play in that either serial killer, Jerry Tyson, is back or a disciple of his has picked up where Tyson left off. While we only got a glimpse of this just before the mid-season finale, it looks like this is building into something that will consume Castle and crew for the remainder of the season. This is a welcome departure from Kate's quest to find her mother's killer, which she thankfully abandoned near the end of season 4. Castle's engagement to Kate, while important, doesn't take center stage in every episode as many shows are wont to do when an engagement is introduced as a plot device. This is an excellent thing as we finally get to see some complex growth from the supporting characters of Esposito, Ryan, Alexis, Lanie and even Capt. Gates. Shiny!