Cote de Pablo is snacking on olives in a hotel bar, considering a key relationship that is about to come into focus again on NCIS, which emerged as TV’s No. 1 show in its seventh season. In a sweeps episode called “Jet Lag,” her character, Ziva David, spends most of the hour trapped on an overseas commercial flight with an unknown killer—but, more importantly, trapped in the company of Michael Weatherly’s Special Agt. Tony DiNozzo, with whom she may forever enjoy an unconsummated sexual tension.

Or is it possible that it was already consummated, years ago, and only she and he—and a minority of alert viewers—figured it out?

“Michael and I have spoken about it lightly, because we don’t want to go into it too deeply,” she says. “But we both have different views on what actually happened in ‘Undercovers’ [the 2005 episode in which Tony and Ziva spent time at a fancy hotel]. In many ways, it’s helped us play out whatever it is that’s happened since [with our characters]. Michael has his own agenda and I have mine, and sometimes it’s a complete conflict of ideas. It’s like the book Men Are From Mars, Women Are From Venus….”

Suddenly the sound of the hotel pianist is overtaken by the tinny strains of…”I Think I Love You.” Weatherly hovers behind us, impishly brandishing an iPhone on which he has cued up an apparently revelatory oldie by the Partridge Family. “He’s been doing that lately,” she laughs, “pulling up that song every time we have scenes of ‘ambiguous sexual tension.’”

Ambiguity, thy name is “Jet Lag.” In the January 26 episode, the noncouple collectively known to fans as “Tiva” is escorting a witness from France back to D.C.; in midflight, they receive intelligence from Gibbs (Mark Harmon) and McGee (Sean Murray) back at headquarters that an unknown would-be assailant is also on board. “It’s a locked-room mystery at 33,000 feet,” says exec producer Shane Brennan. But before that, there are some opening scenes set in the City of Love.

Maybe what Weatherly should be cuing up is the Clash track that goes, “It’s always tease, tease, tease…” As Brennan says, “There’s a lovely sort of undercurrent, because Tony and Ziva have some difficulties in Paris with their hotel room, and we end up not being quite sure what the sleeping arrangements were. And we have a lot of fun with that. It’s the first time we’ve really dipped our toe back in the Tony/Ziva relationship since the big fallout of what happened” after Tony killed Ziva’s Israeli boyfriend at the end of last season.

The episode features another big fight scene, but this time, it’s more mano-a-womano combat. Says Weatherly: “I am knocked in the chest once, out of the frame, and then she has a huge fight sequence to complete. And then I just come in and straighten my tie like Roger Moore and say, ‘I’ll take that hot towel now.’” We’ll see if he’s kidding or just provided a major spoiler.

A 767 jet was re-created on the show’s Los Angeles’ soundstages, with no stinting on the claustrophobia. “It was 14 hours a day in an airplane for three days in a row,” says Weatherly, “so it was essentially like we flew to Greece every day. The good news is that when you’re stuck on an airplane with Cote, you are constantly amused. You’re singing songs from musicals you barely know, like Barnum and Show Boat.” (De Pablo has a musical- theater background.)

At times the realism was terrifying. Weatherly took catnaps between shots and had woozy “moments of sheer panic, because you don’t know what flight you’re on. You wake up and see a dolly grip with his utility belt walk by the wing and you’re like, ‘AHHH!,’ like William Shatner. We reference that Twilight Zone ['Nightmare at 20,000 Feet']. Of course DiNozzo has to go for the Shatner impression: ‘I … can’t … take anymore!’”

Any hints about what some more earthbound sweeps episodes might hold? “In an episode that will air very shortly, Gibbs is hurt,” teases Brennan. The show runner swears—swears—his philosophy isn’t all that sweeps-centric: “When American Idol comes on, we really have an uphill battle. So my attitude is, forget sweeps—let’s just make every episode a sweeps episode.”

The emotional stakes typically don’t get too high on NCIS until the season finale. But de Pablo says the trauma that Ziva went through during her kidnapping and torture at the start of this season hasn’t completely been forgotten amid the current good cheer. “There’s an episode that we just finished shooting, called ‘Masquerade,’ with a scene in which I’m talking about the things that happened in Africa we still don’t know about. In true NCIS fashion, it’s never quite addressed, but it’s implied that bad things happened. The way it was written was sort of glazed over, but it was so there. We’re constantly being bombarded with new information, or else the characters just wouldn’t grow or go anywhere.”

But we don’t have to worry too much for now about Tiva going anywhere, except, possibly, in your imagination. When it comes to the Parisian frolic in “Jet Lag,” says Weatherly, “There are a lot of different ways to watch this episode. If you go in thinking that something happened, this will confirm thinking that something happened. But if you go in skeptical, you might think, ‘Ah, see? They said pretty much that nothing happened.’ It holds up a mirror to your own preconceived idea.”

Cue the Partridges again. “This is where I get into our theme song”—which is purely Weatherly’s folly, and has yet to show up on any episode or soundtrack CD—”and anyone who enjoys the chemistry between Tony and Ziva will understand that it is a theme song of ambiguity. ‘I think I love you!’ Now where does the word ‘think’ come into ‘love’? Right? ‘But what am I so afraid of?’ I’m afraid you might be a Mossad assassin and try to kill me? I’m afraid you might be an irresponsible 13-year-old frat boy who might not take this seriously? I’d like to go on YouTube and find some clever soul out there has fashioned an NCIS clip job to ‘I Think I Love You’ as an ode to the ambiguity of their love, or not-love.”

From your lips, Michael, to the fan base’s ears.