It's All in the Family for Sean Murray when His Daughter Cay Ryan Murray Guests on Tonight's NCIS

It's all in the family for Sean Murray on tonight’s episode of NCIS when his real-life daughter Cay Ryan Murray guest stars as a computer-savvy teenager named Teagan Fields, who is a suspect in a murder case that the team is trying to solve because of her mad computer hacking skills.

This isn’t the first time that Murray has acted with a family member on NCIS. Longtime viewers will remember that Murray’s stepsister Troian Bellisaro played his sister on two episodes of the CBS drama.

“It was different with Troian,” Murray exclusively tells Parade.com, “I didn’t realize how much I separate my immediate family and work. I didn’t realize I compartmentalize them a little bit in my brain. I had this moment of looking up, of us being in the squad room and looking up at the plasma, and my daughter is on the plasma. My brain is going, ‘What the hell is going on? There’s a weird melding of worlds going on.’”

As the resident computer expert, McGee is the obvious go-to guy when the team catches a case involving hacking. There are a group of military teenagers whose parents aren’t paying enough attention, so they get into trouble by setting up parties that include breaking into houses on the base by unlocking the doors using a computer.

“Teagan creates an algorithm to get into these houses, and someone ends up using this algorithm to get into a house and kill a lieutenant,” Murray says, going into more detail. “Since she’s the one who created the algorithm, and according to Teagan, she is the only one who has it, knows anything about it, etcetera, etcetera.”

Related: NCIS Star Sean Murray Teases the 'Amazing' Conclusion to the Story of Why Gibbs Shot McGee in the Season Premiere

Teagan is a disillusioned 15-year-old and McGee butts heads with her because she’s a tough personality, but he identifies with her a lot at the same time. There was an episode called “House Rules” in which McGee wrote a letter to his father, who was an admiral, in which we learned about their dysfunctional relationship. And, because he knows that in order to solve the murder case that they’re going to need Tegan’s help, McGee shares that same story of his issues with his father with Teagan in an attempt to win her over.

“I don’t want to say takes her under his wing because it’s not like that, but they bond a little bit,” Murray adds. “Because McGee was a military brat as well and didn’t have a great relationship with his parents, they kind of form a little bit of a bond over that and she confides in him. She eventually helps us track down the killer and find out what’s going on.”

Acting in this episode of NCIS is Cay’s first proper TV-film credit, but she’s been acting for years in theater as part of the Youth Academy of Dramatic Arts and she attends Alexander Hamilton Senior High Music & Performing Arts Magnet in Los Angeles.

Related: Is Wilmer Valderrama Leaving His Role as Special Agent Torres on NCIS?

“You have these preconceived notions as to what you want your kids to do and all these sorts of things,” says Murray in response to being asked if he is okay if Cay follows him into the business. “And then you learn, ultimately, at least in my case, that you really want them to be happy and you want them to do what makes them happy as long as it’s not something destructive. Acting is where she gets her joy.”

And Murray says he could observe it firsthand on set, but he also had a chance to observe her professionalism, which meant that all her years in her theater program paid off and Cay didn’t come off as completely green.

“When you’re hanging out between filming, while you’re doing a scene and during the camera setups, and you’re sitting in your chairs in your little room waiting during the setups, I’d be there with my daughter, and it didn’t feel like I was hanging with my daughter. I felt like I was with another actor. Which I was, but I think it spoke to her professionalism quite a bit.”

Related: NCIS Adds a New Recurring Character Opposite Special Agent Alden Parker

That doesn’t mean he wasn’t nervous on her first day of shooting.  While he was confident that she would have the acting part down, working on a TV set has a lot more moving parts than a stage production.

“What I was worried about, and a lot of people aren’t aware of the fact until you’re actually doing it, you have 100 people right there on you every two seconds and everyone’s paying attention,” Murray explains. “There’s so much chaos that you can really get caught up in it, and it can take your focus away. I was so pleasantly surprised at how well she handled that and didn’t let all the chaos of the machine of television get in the way. It didn’t overwhelm her. She was able to stay up. She did such a terrific job, I’m so proud.”

Tune in tonight to see the proud papa when NCIS airs at 9 p.m. ET/PT on CBS.

Next, Where’s Gibbs? Everything We Know So Far About NCIS Season 19