The tone of last night's NCIS was more lighthearted than recent weeks. At times, it even bordered on funny. By and large, it worked well, even if we felt a bit less engaged at times.

What began as an investigation of an illegal trucking operation turned into much more. Check out our episode recap for the plot details. Now, here's our review of "Jack Knife" ...

Damon Werth was a Marine who suffered steroid-induced psychoses a few seasons ago. He shows up at Gibbs' house when another ex-Marine, Nick Heatherton, turns up dead.

Ducky suggested Gibbs felt responsible for Damon after saving his life then. This was evident as Gibbs went out of his way to work the case, even if it was the FBI's jurisdiction.

That meant bringing on board old friend/adversary FBI Agent Tobias Fornell (Joe Spano), who had more than one comedic exchange with Gibbs (and slept with his wife once).

McGee (when he was able to stay awake) assisted Gibbs' investigation.

Heatherton was working for the Szwed shipping company driving trucks cross country. The team suspects contents in the semi he was transporting may have been worth killing for.

What those contents were, however, no one knows.

Werth convinces NCIS to let him go undercover (Ziva acts as his partner) to work for Szwed on his next job. They are forced to hijack another truck but still don't know exactly why.

They finally learn what Szwed wants jacked: an expensive car that belongs to ... Szwed. He lost it in a bet to millionaire tycoon David Devoisier. Now he's going to "steal" it back.

Gibbs and Fornell break up the hijacking fairly easily, but there's a twist - Devoisier actually had Heatherton killed to cover up a hit and run he witnessed. That was unexpected.

Watching the mystery unfold is always entertaining but last night was really about characters interacting. Gibbs and Fornell, Gibbs and Werth, and especially Gibbs and McGee.

Having trouble with the long hours, McGee turned into an over-caffeinated mess. That guy does not need 12 sugars to channel his inner McGeekdom, but it certainly doesn't hurt.

Tony and Ziva continued to dance around their Paris trip, and he got a little jealous of her sharing the undercover job with Werth. What is going on there? Will we ever find out?

RANDOM THOUGHTS:

• Best scene of the night: When Gibbs and Tobias pretended to run into Werth and Ziva at the gas station. They squabbled like an old married couple (which they sort of are).
• Quote of the night: DiNozzo: "We got nothing." Tobias: "I don't like the sound of that." DiNozzo: [way more enthusiastically] "WE GOT NOTHIN'!" Okay, that one was good.
• Only Tony would name-drop Robin Hood: Prince of Thieves and Jan Michael Vincent from Air Wolf in a typically one-sided conversation. His film/TV references are great.
• Bringing Werth back into the mix was a nice touch, as we wondered if he would crack under pressure given his past. A random character would've lacked that tension.
• As usual, Abby somehow makes forensics look so cool.

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.