'Castle': Seamus Dever on Celebrating the Best of the '70s in Theme Episode

ABC's veteran procedural travels back in time for a decades-old cold case: the murder of an infamous NYC crime lord.
Danny Feld/ABC

Castle is going back to the 1970s.

When the body of an infamous New York mobster who disappeared in the '70s is discovered, Beckett and Castle try to solve the decades-old Mafia hit. Their only witness? A man who thinks it’s still the '70s, so to find out what he knows, the detectives of the 12th Precinct must pretend like time has never passed.

"There's a lot of hair," Seamus Dever (who plays Det. Ryan) says to The Hollywood Reporter with a laugh. "The '70s are a lot about the hair. Hair on your face, hair all the way down to your head. You think, 'There's going to be a lot of maintenance.' They gave me a big, flowing blond wig and I kind of disappeared. People stopped recognizing me."

The long-running ABC crime procedural is known for special themed episodes, but as Dever tells it, this one is up there. "The crew got a kick out of it and there was a nice spirit on set with lots of laughter," he says.

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"They wanted me to contrast to Esposito," Dever says of his '70s look. "There's only so much that Jon [Huertas]' hair can do; he's going to have some kink to it and that's cool. So they said, 'OK, we'll make [Ryan] blond.' " The only suggestion Dever made that was incorporated into the wardrobe was the sideburns and the mustache ("how big I wanted it or how trim I wanted it").

With the new alter ego comes "a cool, more in-charge Ryan," Dever says. "You get to see Ryan a little bit smoother than he really is. Ryan's known as that square guy with the sweater vest and the three-piece suit, so this is very different. He's got a shirt undone until the middle of his chest. We get to see a different side to him because of that."

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In terms of solving the cold case, the road may be rocky, but Dever is confident that the NYPD's 12th Precinct is successful in catching their guy. The episode also features a guest turn by Jon Polito, frequently featured in the Coen brothers' movies, as the man who can't fast-forward to 2014. "We take him to a '70s club to jog his memory," Dever says. "We had so much fun with Jon that we were feeding him lines to say, things he could get away with."

As for memorable moments or quips from the hour, Dever hints of a grandiose speech. "Ryan starts off [the episode] very reluctant about dressing up like this and he blames Esposito for this stupid idea. There's a moment when Ryan turns and he's going to take charge of this. There's a little speech he does and at the end, Ryan says, 'Can you dig it?' " Dever says, referencing a line made famous by the 1979 cult classic The Warriors. "That was a lot of fun."

Castle airs Mondays at 10 p.m. on ABC.

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