Castle Preview: Ryan's 'Badass' Undercover Self 'Surprises the Hell Out of Everybody'

Castle Season 5 Spoilers Ryan JennyThis week on ABC’s Castle (Monday, 10/9c), Detective Kevin Ryan (played by Seamus Dever) must slip back into an alias he used years ago while working narcotics — revealing to his pals at the 12th a side they’d never seen and putting a fiery old flame in close proximity.

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When a man is found dead in an industrial cake mixer (was he battered?), the investigation leads Beckett & Co. to Siobhan O’Doul (Cara Buono, Mad Men) — a beautiful bar owner with whom Ryan has a complicated history from his days undercover with a Staten Island mob.

“She was basically Ryan’s girlfriend,” Dever tells TVLine, “so we get to see a lot of him making amends to her. There’s a lot of making up and doing the right thing for her, to help her out of the current situation.”

To that end, Ryan dusts off his old undercover persona, Fenton O’Connell, to delve back into the underworld of the Irish mob.

“You see Ryan immerse himself and play a different character, basically,” says Dever. “You’re going to realize that he’s not just that guy in a tie and sweater vest. He has a very dark past that gets to come out.”

“This episode features Seamus in a way that we have not been able to feature him before,” affirms series lead Nathan Fillion. “We’ve got all these wonderful, talented actors on this show, so to be able to take them out of their wheelhouse of what they’re usually doing and say, ‘This guy has a life outside of his cop-ness that we see all the time, he has history, he has other things going on,’ is very exciting.”

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Ryan’s colleagues meanwhile are a bit taken aback to “meet” his alter ego. “NATHAN FILLION, JON HUERTAS, SEAMUS DEVER, JULIANA DEVERAs Ryan assumes his old persona and sees if he still has the ‘juice’ to do what he used to do, it surprises the hell out of everybody,” Dever previews. “They’re like, ‘Oh my God, he did that…? What?!’ Everyone sees this mild-mannered family man, but here he gets to be a badass.”

Alas, Ryan’s wife Jenny must also lay witness to this transformation — and just as they’re laboring to put themselves in a family way. “Jenny comes back and we get to see the progress they’re making in trying to have a baby,” Dever says. “There’s some lovely work by my wife Juliana [Dever], which is a real treat.” (As previously reported, the wannabe parents will have either a thumbs up or thumbs down to share by the end of the episode.)

All told, Dever describes the Ryan-centric hour as “fun” and “dark and interesting.” The actor raves, “Terence Winter wrote us an amazing episode, so I hope it all turns out, because on paper it was amazing.” (With reporting by Vlada Gelman)

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