Dizi Adı: Castle
Bölüm Adı: Linchpin (2)
Sezon/Bölüm: 4. Sezon 16. Bölüm
Yayın Tarihi: 20 Şub. 2012

Castle & Beckett race to find the “Linchpin” in order to stop the first domino in a chain of events which will plunge the United States into war. Their efforts continue to put Castle in contact with Sophia Conrad – a smart, commanding and sexy CIA operative who was Castle’s inspiration for Clara Strike in the “Derrick Storm” series of books; and intelligence officer Martin Danberg is back.