One of the most important things a TV Series needs is fantastic chemistry between the two leads and this show has it in spades. Nathan Fillion and Stana Katic are brilliant together despite their characters looking at things from completely different points of view. Nathan's character Richard Castle is a witty, clever, if a touch annoying author who scores himself a spot on Det. Kate Beckett's (Stana Katic) team and together they solve murders. Kate is a tough no nonsense detective with a troubled past who initially despises of Castle's presence but eventually warms up to him as he proves his worthiness over time in her team.
With a great supporting cast and brilliant scripts this show is quickly becoming a popular phenomenon and should hopefully be around for quite a while yet!