Watch Castle Season 3 Episode 21 online via TV Fanatic with over 7 options to watch the Castle S3E21 full episode. Affiliates with free and paid streaming include Amazon, iTunes, Vudu, YouTube Purchase, Google Play, TNT, and Verizon On Demand.
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When a champion swimmer is found dead in a training pool, Castle & Beckett dive in to investigate his murder, and uncover myriad secrets.