The Best of Both Worlds, Part II
The first episode of the fourth season — a sensational climax to one of the most exciting Trek story arcs ever — was groundbreaking in several ways. "The Best of Both Worlds" was the first two-part storyline in Star Trek history to bridge two seasons, and it marked the first Star Trek series to make it past the three season run of the Original Series. This episode also reveals that Starfleet and the Federation are vulnerable to invasion by a powerful entity, one that would continue to haunt them for several years to come.

Family
Virtually a sequel to "The Best of Both Worlds, Pt. II," "Family" was the first episode of Star Trek to introduce so many family members of the Enterprise crew in one go. The episode also broke tradition by being, the first Trek episode without a single scene on the Bridge. Stepping away from the confines of Starfleet, we get to see Captain Picard become, simply, a member of his own family, as he deals with the completely different set of circumstances that lifestyle can offer. We also see Worf's adoptive human parents, Sergey and Helena, not to mention Wesley Crusher's dad, Jack, via a touching holotape made when the young Crusher was but a baby.

Brothers
Two brothers mechanical, two brothers human — both sets have their stories. Credited to series executive producer Rick Berman, this episode neatly tie together the differences between siblings and the love that binds them. Data and Lore are reunited once again, both responding to a homing signal from their "father," Noonien Soong. Lore wants the emotion chip intended for Data, and deceives and murders to get it. Meanwhile, aboard the Enterprise, young Willie Potts is near death following a joke gone wrong at the hands of his elder brother Jake. The two stories dovetail nicely, and Data is left wondering at his own potential for emotion.

Legacy
On Turkana IV, the Enterprise crew is surprised to learn of the existence of the late Tasha Yar's sister, Ishara. Yet another of Season Four's "sequel" shows, "Legacy" gives us a posthumous glance at the life and environment that spawned Tasha Yar. Her sister, Ishara, is at times dismissive of Tasha for leaving her homeworld and her bitterness ends up biting a helping hand. The lessons learned in this episode focus on betrayal, and the deep-rooted feelings that go along with this powerful emotion. But a memorable and continuing theme of family — and the fact that Starfleet officers have them, too — is something that would be key to the foundation of the following series, Star Trek: Deep Space Nine.

Reunion
Another "family affair," "Reunion" focuses on the relationship of the half -human/half Klingon ambassador K'Ehleyr and Worf, her former lover. When K'Ehleyr returns to the Enterprise in this episode, she brings news of problems in the Klingon Empire — Chancellor K'mpec has been poisoned. She also has a young boy with her named, Alexander. The product of their last reunion, Alexander represents new challenges to Worf that will resonate throughout the rest of TNG's run and into the next series, Deep Space Nine. The poisoning of K'mpec also represents a portent of things to come with the continuing saga of the Klingon Empire.

Data's Day
Data's Day stands out for several reasons. It marked the first time a Star Trek episode was presented in the "day in the life" format, as we follow Data's ongoing study of humanity. "Data's Day" also contains lots of juicy Trek trivia bits for the discerning fan: Data's cat is introduced, although not yet named, and the wedding featuring O'Brien and Keiko contains a speech by Picard that was lifted almost word for word from Kirk's wedding speech in "Balance of Terror." There's also a subplot concerning Romulan subterfuge, but it's almost lost amongst the delight inspired by seeing Data dance.

The Wounded
One word: Cardassians. "The Wounded," another landmark TNG episode, introduces an alien race that would go on to have far-reaching story implications for TNG, , Deep Space Nine and even Star Trek: Voyager. In this episode, we get some backstory on Lieutenant Miles O'Brien and how he served with Captain Maxwell, a renegade Starfleet officer who is attacking Cardassian ships, thus threatening a fragile peace between the Federation and the Cardassian Empire.

QPid
Every Star Trek series has at least a handful of comic relief episodes, and TNG is no exception. The potential for humor whenever Q returns is always there, but perhaps never more so than in "QPid." With the main bridge crew decked out in Robin Hood-era wardrobe, Q puts Picard to the test once more, this time in the name of that most human of emotions,love. The return of Vash ("Captain's Holiday") is also welcome. She would return to Star Trek only once more in the Deep Space Nine episode "Q-Less." Worth watching for Worf's declaration that he is not a merry man. Priceless.

The Drumhead
Just another one of Starfleet's mad admirals, or genuine high-level intrigue aboard a starship? "The Drumhead" is one of those classic courtroom-type dramas ("The Measure of a Man," "Court Martial"), offering great plot twists aboard an emotional see-saw. Veteran actress Jean Simmons reveals a troubled former commander in an excellent performance as former Starfleet admiral Nora Satie, while Jonathan Frakes turns out to be a confident director in this, his second time at the helm.

The Host
The Host is yet another of the fourth season episodes of TNG that paved the way for several species and relationships that would carry on far into later episodes and other series. In this, Dr. Crusher gets a romantic storyline and the Trill race is introduced. Although the Trill in this episode, Odan, doesn't resemble a typical Trill we see later in DS9 (Ezri or Jadzia Dax), the biology is at least established: a humanoid host carries a worm-like symbiont and the two co-exist with shared memories.

In Theory
A Data episode, "In Theory" poses the question of whether an android can love. This one cannot, but it's the journey he makes with a fellow crewmember, Jenna D'Sora, that makes this episode memorable. Data creates a special program to guide him in the ways of love — the only problem is that the android is simply incapable of being emotional, something love tends to thrive on. His new "girlfriend," D'Sora, realizes that Data is about as emotionally deficient as her last boyfriend and breaks the cycle. But the lesson is learned — Data is a hopeless romantic.

Redemption, Part I
In what would be one of Star Trek's most enduring story arcs, beginning with "Sins of the Father" and carrying over into the next series, Deep Space Nine, ", Redemption, Part I" provides a further glimpse into the inner workings of Klingon politics, and the deadly machinations that come with it. With Picard acting as the Arbiter of Succession in the installation of Gowron as Chancellor, the Starfleet captain chooses not to become involved when the Duras family returns once again to try and claim their House's right to the throne. In an emotional finale, "Redemption, Part I" sees Worf resign from Starfleet.

Did we leave out your favorite episode? Go to the message boards and tell the world what you think.