Nathan Fillian was in the Josh Weldon universe in Buffy and Firefly, then in Castle on ABC, his portrayal of Officer Nolan has a charm to it because he's not afraid to be wrong or go out on a limb. Melissa O'Neil was great in Dark Matter and brings her character, Officer Chen, good depth because she dials down the physicality she used in Dark Matter but still has the ability to do physical cop work, and I'm glad they don't do female officer in distress too much in the series. It is a synergy of good casting, smart dialogue and not over the top situations. It isn't Hill Street Blues or NYPD but it isn't supposed to be so I can just sit and enjoy the show.