For a show frequently tagged as a procedural, NCIS weaves remarkably intricate, ongoing story lines. Last night's episode, "Patriot Down," wouldn't have the same impact had you not watched the previous week, or this entire season, or perhaps the entire series.

The two-part seventh season finale, beginning Tuesday and to be continued next week, is shaping up to be the culmination of much more than that as Gibbs' long-buried past is finally coming to light, courtesy of unknown forces. He's reeling and so are we.

Like last week's "Borderland," the murder in "Patriot Down" seemed unrelated to the escalating, shady plot to destroy Gibbs at first, but connections were made before long.

Special Agent Lara Macy, familiar from last season's "Legend," (and referenced last night on NCIS: Los Angeles) was not just found dead, but in Annapolis, NCIS' jurisdiction.

Someone wanted her to be found by Gibbs' team.

As Ducky discerned, whomever killed Macy wanted her to be found by NCIS.

It appeared as though Macy may have been killed after investigating the rape of Petty Officer Kaylen Burrows. Privileged college student Tyler Hammond was a prime suspect.

His story didn't add up and after Burrows was assaulted by Burrows' fellow service members, suspicions fell on them as well. But it was Hammon behind it - and his father.

Disturbingly, Burrows was sexually assaulted by Tyler and Randall Hammond, a D.C. construction tycoon, a fact unearthed by Gibbs during an intense interrogation scene.

But these two didn't kill anyone.

When Ducky learns that Macy was killed with precision by an Army-issued knife, Gibbs realizes what he'd suspected all along: Macy's death had nothing to do with the rape.

It had everything to do with him.

Macy being killed in such a violent way, with a signature Army Ranger, was proof that she was targeted. As was the fact that someone had stolen some of her old notebooks.

Not regarding the Burrows case, but from way back - 1991-1992, when she was an MP at Pendleton, and around when Gibbs killed Hernandez. It's all coming together now.

You can see how it pains Gibbs to lose control, to be jerked around as he so often does to adversaries, and especially to see those close to him in peril. He is unusually tense.

He suspects that Mike Franks may be next , and makes a frantic call to his local bar in Mexico, telling the owner to relay a simple message: Rule #44. But is he too late?

The big twist came at the end, with Gibbs on the Mexican coast, a scene that opened the episode before the credits, and took place four days after the murder of Lara Macy.

Finding a body he believed to be Franks in the sand, Gibbs was cornered and disarmed by Lt. Dean, Col. Bell's right-hand man, and who NCIS had linked to Macy's death.

Lt. Dean revealed that the dead body they were standing over was not Mike Franks, but Col. Merton Bell. Gibbs: "Who are you really working for?" *THUD* End scene.

How will Gibbs get himself out of this one?

We never guessed that "Patriot Down" referred to Bell as well as Macy. Allison Hart always terms Bell a patriot, and while he'd been digging into Gibbs, this runs much deeper.

It appears as if the Reynosa drug cartel may be behind the killings, and that Paloma Reynosa may be looking for revenge herself. Could she be Pedro Hernandez's daughter?

This should be very interesting to watch play out, as Hart suggested Bell was "involved" with the narco-terrorists in some fashion. But why did Dean turn on his boss, Bell?

One theory is that Bell was working with them (and Hart, who helped drum up the cold case) to expose Gibbs, but the cartel had far greater and sinister motives - murder.

With Gibbs captured, it looks like he's up against it, but from the way Vance put the smack down on on Hart, you know he's going to do whatever it takes to get him back.

Does this put to rest doubts as to the director's loyalties? Where does Hart fit into the equation now? Either way, looks like we're in for a terrific season-ender next Tuesday.

Other thoughts, observations and lingering questions:

• What is Rule #44?
• Tony lines of the night: To McGee: "What kind of boy scout are you?" "Who are you, Bobby Flay?" On what Ziva's graduating from: "English as a 10th Language."
• Abby kept probing Gibbs for cues as to what do with the evidence, and after avoiding questions all night, he ultimately told her to do one thing: her job. Exactly.
• If we remember correctly, Lara Macy was the one who ruled Gibbs' shooting of Hernandez justifiable and didn't include any evidence to the contrary. Interesting.

What did you think of last night's NCIS? How will this play out next week? Do you agree with our theories above or have your own? Comment below!

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