This was a typically strong episode of NCIS, perhaps more so than most recent efforts. There was a ton going on, and a more compelling murder mystery than usual.

"Obsession" began with the murder of Navy Lt. Craig Hutton, which proved a tough case to crack, and one that unmasked long-buried secrets from the Cold War era.

It's a testament to the show's terrific writing that a seemingly run of the mill NCIS investigation can snowball into something much bigger seamlessly and plausibly.

When Lt. Hutton's car drives out of control and hits a parked vehicle near a hospital, he is dead, yet not from injuries from the accident. It was something internal.

In an attempt to reach his next of kin, NCIS learns that his sister is popular ZNN reporter Dana Hutton, who is strangely missing, and who Tony has a thing for.

Gibbs stumbles upon some Cold War accounting.

Even more strangely, her old friend Charlie Banscom, recently died and Dana was the executor of his estate. In that capacity, she learned who Banscom really was:

Yuri, a highly-connected KGB agent and "handler."

Abby and Ducky were long flummoxed by Lt. Hutton's death, but Palmer eventually discovers a microscopic pellet in his shoulder, filled with ricin, a deadly poison.

This was old school KGB: Inject someone with this and they die in a few days, without a trace of who did it, and no antidote to stop it. That's what did in the officer.

The most shocking scene of the night came when Tony tracked down Dana, who revealed she'd been injected too. By whom? No idea. But she was toast, and knew it.

Dana used her brother’s Navy clearance to dig into Charlie’s past. The subtle murder clue came in the form of his bookstore, which she now had to sell as executor.

Gibbs finds a microfiche - Quickbooks, 1970s style - in the store of all of Charlie’s accounting and he and Vance were thus able to ID everyone he did business with.

Specifically Maggie Reed, the real estate agent who was trying to hunt down the secret agent's slush fund and killed off both of the Huttons for getting too close.

It was a great twist to end a particularly good episode that featured plenty of side plots along with the main mystery. Most notably, Tony's obsession with Dana.

Perhaps DiNozzo needs to get out more. All the movies might be messing with his head a little, because he seemed enraptured by the idea of her from the start.

What would Brenda Bittner think?

Tony toed the professional and personal line last night.

The scene in her house were Ziva called him out on it was terrific, and overdue, and Tony definitely realized how close he'd come to crossing the line after Dana's demise.

He admitted breaking rule #10 - never get personally involved in a case. Gibbs could relate, saying it's the rule he has the hardest time following as well. Speaking of ...

Vance introduced us Alejandro Juarez, from the Justice Department in Mexico. He's working on an international task force with NCIS and has temporary employee status.

His attorney? None other than M. Allison Hart (Rena Sofer).

This resulted in typical unspoken tension between Gibbs and Hart, and we learned in passing that Col. Bell has been sprung from prison due to the legal eagle's handiwork.

Initially, it looked like private military contractors such as the one run by Col. Bell could have been behind the Huttons' killings, as Dana was doing a big expose on them.

Lt. Hutton was researching such companies, and was about to recommend the government cut some loose. Hart was her usual smug self, and Gibbs remains captivated.

This development had nothing to do with the killings in the end, but likely set the stage for coming episodes. What is Hart's endgame? Will Bell seek revenge on Gibbs?

Other thoughts and observations:

• Juarez is an admirer of Abby and invited her to come to Mexico to speak at a symposium he's holding. We can't wait to see Abby (and McGee) south of the border.
• Extremely cever move Banscom used the cash to buy extremely rare, first edition books - worth millions, hiding in plain sight. The Realtor missed the boat there!
• Appropriate that Ducky ultimately discovered the cause of death in this case (with a major nod to Palmer), given David McCallum's history as Russian secret agent Illya Kuryakin­ in the hit '60s series The Man from U.N.C.L.E. He's the best.

What did you think of last night's NCIS? Do you like were the show is headed as we gear up for the Season 7 finale? Leave a comment with your thoughts.

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