The second season of NCIS: Los Angeles came to a mysterious, dark conclusion last night.

More questions were posed than answered, but what we did learn was very much unexpected, dramatic and enough to keep us riveted heading into the fall.

On the heels of a head-spinning NCIS season finale, LA couldn't help but feel less important, but the team's search for Hetty wasn't a letdown by any means.

We knew going into "Familia" that whatever sparked her resignation from NCIS was related to Callen, but what unraveled in Prague was still a huge surprise.

Operation Comescu is, as we understand it right now at least, Hetty's plan to protect Callen from an Eastern European crime family who wants him dead at all costs.

They believe he is the last member of another family, their sworn enemies.

In typical Vance fashion, he tries to keep Callen OUT of the loop, or on a "need to know" basis, eventually driving him over the edge and prompting him to go rogue.

Callen wasn't buying for a second the notion that the Comescu family mistakes him for someone else. Nor was he about to respect the authority of Lauren Hunter.

Chris O'Donnell did a nice job of displaying the pain, fear and uncertainty Callen must feel. Not only is his past a huge mystery, now his mentor is deeply enmeshed in it.

The second season concluded similarly to the first, with Callen inching closer than ever to learning who he is, but with much more on the table - and at risk - this year.

In the closing moments, Hetty brings the "Familia" a false death certificate and claims that they can stop looking for Callen, as the man they seek is already dead.

Why would they possibly believe the diminutive Hetty?

Just when it started to make sense, she flashes an insignia suggesting she is Comescu, as well. That's a "distinguishing feature" all right. What a way to end the season.

Among the burning questions we're left pondering:

• Is she really part of the family of masquerading?
• Do Nell and Vance alone know Hetty's real name?
• Why resign from NCIS to embark on this mission?
• Did she take Callen away as a baby to save him, then hide his identity from everyone (including himself), then groom him for this job from the start?

One thing that appears (partially) clear is that Callen really is a descendent of the other Romanian family. The childhood flashbacks seem to suggest as much, as does the fact that Hetty went to such great lengths to protect him in Prague.

Also clear? The team is in grave danger. While Hetty tries to pass him off as dead, she has no idea G is stepping into the lion's den right beside her in Prague.

This story arc could take any number of directions next season, but it looks inevitable that Callen will be revealed, intentionally or otherwise, to the Comescu.

The NCIS: Los Angeles finale built slowly to the cliffhanger ending, but planted intriguing details throughout to make you think and eagerly await what's next.

Some of the lighter moments were missing this week, but given the circumstances, that was appropriate. This was a very big deal - more so than we expected.

Rocky Carroll raised the stakes from the start by guest starring as Vance, while Claire Forlani's Special Agent Hunter made quite the multilingual introduction.

Needless to say, it remains to be seen how she remains in the fold, if at all, when Hetty returns to the helm. Things look bleak now, but no Hetty, no show.

Linda Hunt's character has become the glue of NCIS: LA, and seeing her in a new setting, wielding her power outside the office, only heightens her appeal.

It wouldn't be the first time the NCIS franchise has let a main cast member go unexpectedly, but we don't see it happening in Hunt's case. We hope.

What did you think of the NCIS: Los Angeles season finale? Discuss!

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