NCIS: Los Angeles

When last we saw Peter Cambor on NCIS: Los Angeles, his character, operational psychologist Nate Getz, was packing up his office for a secret assignment.

Exclusive: What's next for NCIS: Los Angeles' Nate?

Nate returns in Tuesday's episode, and while the team reunion may be sweet, don't expect an abundance of revelations about Nate's disappearance.

"The mystery still remains as to where exactly he's gone, but what you need to know is he's done some special training to improve the skill set he already has," Cambor tells TVGuide.com. "You get to see my new skills come to use, and I'll say it's not like he went to typing school."

Indeed, Nate goes undercover at a prison with Sam (LL Cool J) in an effort to take down a renowned terrorist operating behind bars, and things definitely get physical. Cambor says Nate's new abilities, which he's learned at the request of Operations Manager Hetty (Linda Hunt), catch all of his former teammates off-guard.

Check out photos of the NCIS: Los Angeles cast

"It's definitely a surprise for everyone," Cambor says. "He was probably incapable of even holding a gun for fear of shooting himself and now is in a situation where he's very much in the front line. Everyone's a little leery at first, but they'll see how he does.

"Nate's capacity before was useful to a point, but now Hetty can really in some way exploit that and make him into a more useful weapon," he continues. "Whereas my strength was more intellectual before, now she's building upon that to make me something different."

Sadly for Nate fans, this return appearance is likely indicative of the role his character will play. "I think he is, as of now, a man of mystery," Cambor says. "He comes in for this job ... and there's a good chance he'll come in for something like this later in the season. But we don't know when and in which capacity."

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And Cambor, who is shooting a comedy pilot for TBS called The Wedding Band, is OK with that.

"[NCIS: Los Angeles] is a show that's going to be on for a long time and these shows change and ebb and flow," he says. "These shows are always a morphing thing to keep it fresh. The thing about the Nate disappearance is it keeps people on the edge of their seats. This episode is a nice little piece for everybody dying to see him again. He's part of the team but the team is always changing."

NCIS: Los Angeles airs tonight at 9/8c on CBS.