侦探小说家Richard Castle(内森·菲利安 Nathan Fillion 饰)一边进行着自己的创作,一方面依然担任纽约警局的“兼职工作”。虽然目前与前妻Gina(莫奈特·玛佐 Monet Mazur 饰)重归于好,但心中总是放不下在纽约警局的半个“搭档”——侦 探Kate Beckett(斯坦娜·卡蒂克 Stana Katic 饰)。而此时Kate的生活中出现一个令Richard警惕的家伙——她当实习警员时的训练师(维克多·韦伯斯特 Victor Webster 饰)。不过让他头更痛则是小大人女儿Alexis(莫莉·奎恩 Molly C. Quinn 饰)开始恋爱,导致他对女儿的男朋友总是疑神疑鬼。 本季的最后,Kate在的葬礼上中枪,让Richard再也无法忽视自己内心的想法,终于对她说出了爱的表白,似乎一切都将不同......Beckett hasn't heard from Castle since he left for the Hamptons months ago to finish writing his second Nikki Heat novel, "Naked Heat." The most Beckett, Ryan and Esposito have seen of Castle is a bookstore standee of him advertising an upcoming book signing. So when Beckett and her team burst into a shadowy apartment on the trail of a murderer, the last thing they expect to see is the real-life Castle standing over a dead woman's body holding a gun. As Castle protests his innocence, Beckett has no choice but to arrest him on suspicion of murder.