"Lower Decks" is a uniquely rare perspective in the TNG annals. Here's an episode told from two points of view: the regular characters we're used to, and also four young junior officers who serve under them. Seeing this perspective is strikingly refreshing, because you get the sense of how Starfleet is not simply this narrative vessel we take for granted, but an organization made up of many people who also view it as their careers.
These four junior officers are friends who hang out a lot together in Ten-Forward. Ensigns Sam Lavelle (Dan Gauthier) and Sito Jaxa (Shannon Fill) are both up for the same promotion to lieutenant. Riker will be the one making the decision of who gets it. Meanwhile, Nurse Alyssa Ogawa (Patti Yasutake) is up for a promotion of her own in sickbay. Ensign Taurik (Alexander Enberg) isn't up for a promotion, but he's ambitious when it comes to engineering enhancements, which can sometimes be a thorn in Geordi's side. Spending time with the junior officers reveals a side of the Enterprise we haven't really seen before, and certainly not in this depth. (We even learn that ensigns must have roommates.)
There's a certain fascination in seeing how the junior officers view their superiors, and vice versa. Lavelle feels intimidated by Riker, who himself finds Lavelle a little "anxious to please"; there's a scene where Lavelle tries to have a friendly drink with Riker and the awkwardness of the situation, however mild, is magnified tenfold simply because of the chasm that separates the ensign from the commander. Similarly, look at how Taurik wants to mass-implement his engineering enhancements prematurely, which seems to annoy Geordi. What Taurik doesn't see — and we do — is the big picture where Geordi has to run an engineering department as a cohesive functioning unit and not simply a lab where a theoretical idea can be rolled out at will.
As sort of a narrative conduit between these two perspectives is Ten-Forward barkeep Ben (Bruce Beatty), who is able to move effortlessly between both worlds because he's a civilian who doesn't have a stake in the career game. He's friends with everybody and can see and hear what's going on from both ends. (One wonders if this character is meant to be a stand-in for Guinan; was Whoopi Goldberg unavailable? But Ben is specifically enough drawn in his social demeanor that I accepted him as just another new character alongside all the others.) There's a standout scene where the junior officers' poker game is crosscut with the senior officers' game, and their complementary discussions are revealing and insightful.
The fresh perspective isn't the only thing that makes "Lower Decks" so memorable. This is also an episode that takes an unblinking look at what it means to be a Starfleet officer (from the more military aspects of the organization) and the sacrifices that come with it. The plot documents political intrigue near the Cardassian border, a secret mission, and a mysterious passenger. The junior officers all get pulled into this mission in one tangential way or another — mostly on a need-to-know basis when it comes to the particulars of the facts. They are mostly in the dark for a long time.
Ensign Sito's role is the most crucial. Sito, you will remember, was the academy cadet who, along with young Wesley Crusher, covered up the death of a fellow cadet who died in a flight accident in the also-terrific "The First Duty." That fact is critical to the effect of "Lower Decks" for many reasons, including the way it drives the plot and characters — but especially in how it makes the arc of Sito's story all the more tragic and affecting than if she had been a character we'd never met before. We are more invested in Sito's fate because we understand why she feels the need to redeem and prove herself for her well-known past transgression.
This is made abundantly clear from the early scene where Picard "tests" Sito by savagely berating her for that past sin. This scene shows just how scary and intimidating Picard can be when he wants to be, particularly as seen from this uniquely vulnerable point of view. (And when we first see this scene, we don't know it's a test; everything Picard says, while harsh, is plausible and grows from past facts.) In reality, Picard brought Sito to the Enterprise to give her the fair shake she might not have gotten somewhere else. But in retrospect, Picard's gambit — to first unload these harsh words and then later recruit Sito into the dangerous mission — almost comes off as a calculated manipulation to get an impressionable young ensign to step up and volunteer.
Meanwhile, Worf's role as Sito's mentor is also a great notion, revealing a corner of a character that you sometimes imagine as existing off screen but rarely get to actually see. He gives her a crucial piece of advice about being judged fairly that moves her to stand up to Picard. (This whole episode feels like an exercise in revealing how the margins of TNG were there all along, waiting to tell their stories.)
I won't belabor the meat of the plot of "Lower Decks," although it's first rate, and it smartly ties the ensigns together, who aren't allowed to talk to each other about their involvement in it. There's a mysterious Cardassian patient for Ogawa (who is actually a Federation spy); there's Taurik assisting Geordi in intentionally damaging a shuttle; and there's Sito doing the heavy lifting by accompanying this undercover operative back to Cardassian space — a perilous mission from which Sito, tragically, does not return. Her loss is a punch in the gut for the four friends, and particularly for Lavelle, who ends up getting the promotion in part because Sito doesn't survive to compete for it. In the end, "Lower Decks" is a brilliant episode of TNG that shows how some Starfleet careers are made with some bitter pills to swallow ... while others — who choose to risk all and step up in the name of the uniform — are cut short.