James Brolin, Nathan Fillion

Who knew? Barbra Streisand is such a fan of Castle (and is pals with one of the producers) that she persuaded husband James Brolin to ­appear on the ABC crime drama. He plays the long-lost father of Rick Castle (Nathan Fillion) in the February 25 episode, the second hour of a nail-biting two-parter that begins February 18. Executive producer Andrew Marlowe is keeping details secret but says, "There will be a moment between father and son when Castle comes to a realization and the two men confront the realities of their relationship."

The emotional episodes also showcase young Molly Quinn, whose character, Alexis, gets kidnapped. "She tries to escape any way she can but keeps getting thwarted," Quinn says. "Near the end, Alexis kind of falls apart."

Marlowe says Fillion lets the tears flow as he portrays the powerless dad who fears for his child's life. "We're giving Nathan the opportunity to show some colors and tackle a range of emotions he doesn't always get to show," says Marlowe, hinting that Castle's father figures into the kidnapping "in a very interesting way. He has a strong hand in how ­everything gets resolved."

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