"Castle" Season 6 episode 12 is called "Deep Cover." The episode will see the return of actor James Brolin to reprise his role as Castle's father, Jackson Hunt. The new murder investigation will lead Castle and Beckett to Castle's father.

Castle and Beckett will be investigating the murder of a young video store clerk. The past record of the murdered victim shows him as a high profile hacker. In the preview video, one can see that the sketch of the suspect has a striking resemblance to Castle's father. The preview clip also shows Castle's father hugging his son. Beckett is unaware about Mr Hunt being Castle's father and in the preview clip one can see her accusing Castle of harbouring a fugitive.

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It looks like Castle's father might not be a completely good man. Brolin had said to Antenna Free TV: "Well, there's no reason for me to do another episodic show...unless I can show you the complete other side of this character, the one you might be afraid of." He had said that if he is going do another episode he would like his character to be "talked-about as the first one."

Andrew Marlowe, creator of "Castle," had told T.V Line that Castle and his father will get to meet again. The episode "Under Fire" is likely to show Castle beginning to wonder "whether he can trust this mysterious stranger [father]." The father and son had first met when Alexis was kidnapped in Season 5 of "Castle." Mr Hunt, an alias of Castle's father as a CIA agent, had helped Castle to find Alexis. He had revealed to Castle at the time that he is his father and is a CIA agent.

Official Synopsis of "Castle" Season 6 Episode 12, "Deep Cover': "The murder of a young video store clerk takes a strange turn when the team discovers his past history as a high-level hacker. But it's nothing compared to the shock Castle receives when their investigation leads them straight to his father, Jackson Hunt."

The episode is written by Terence Paul Winter, while Tom Wright has directed it.