Star Trek: The Next Generation took fans into the 23rd century and presented some of the most compelling science fiction in TV history. Occasionally, the exploits of the U.S.S. Enterprise-D were too much for one simple episode, and the stories branched out over two.
Whether it was gripping tales of The Borg invasion, or Worf's personal journey within Klingon society, the two-part episodes of TNG were often some of the most exciting of the entire series. Although all of the two-part episodes are memorable in their own right, some garnered much higher scores on IMDb.
Birthright Part 1 & 2 - 7.6/7.3
Worf's struggles with his Klingon heritage was one of the most compelling arcs in TNG, and the episodes "Birthright" brought it to the forefront once again. While visiting Deep Space Nine, Worf learns that his father is still alive and he is determined to track him down. Worf's search leads him to a former prisoner of war camp where Klingons and Romulans live in peace with one another.
Worf is doubly challenged in the episodes because he must reconcile his desire to clear his family name, with his overwhelming distrust of Romulans. Generally considered one of Deep Space Nine and they would get a chance to follow his quest for acceptance once again.
Gambit Part 1 & 2 - 7.8/7.9
Usually, TNG's two-part episodes had important implications for the show moving forward, but occasionally they would simply tell a compelling story that was too long for one episode. "Gambit" takes place after the apparent death of Captain Picard, and Riker is put in charge of the intense investigation. When he is suddenly kidnapped by a group of archeological thieves, Riker finds that the Captain has seemingly ed with them.
Further fleshing out Picard's intense love of history and archaeology, the episodes are a fun adventure romp that sees the Captain and his first officer working together. Picard was not often put in the action hero role, but he excelled on the few occasions that he was. While the story might not be as earth-shattering as other two-part episodes, it was an intriguing adventure that harkened back to the earlier days of the Star Trek franchise.
Descent Part 1 & 2 - 8.1/7.8
While they only appeared a few times in TNG, The Borg proved to be one of the strongest alien races in the entire franchise. "Descent" finds the crew once again in conflict with the Borg, but to everyone's surprise, both the Borg and Data experience a range of human emotions that they hadn't previously shown. Digging into why they are suddenly feeling things, the crew encounters another old foe in the form of Data's brother, Lore.
Data's flirtation with human emotion was a thread throughout the entire series, and it was interesting to see him experience them in the episodes. The Borg are just as frightening as ever, but the added wrinkle of emotion adds an element of humanity that lessened their usual impact. The heart of the episodes was Brent Spiner's terrific turn as both Data and Lore, and he was able to imbue both characters with their own distinct personalities on screen.
Unification Part 1 & 2 - 8.2/8.3
In one of the best episodes about the Vulcans, "Unification" reunited Trek fans with their favorite pointy-eared hero. Ambassador Spock has gone deep into Romulan territory, and the Enterprise has to track him down in order to ascertain why he seemingly defected from the Federation. Once on Romulus, Picard learns of Spock's ambitious plan to bring peace between the Romulans and their distant Vulcan cousins.
Giving fans their first up-close look at Romulan society, "Unification" was an absolute treat for longtime Trek viewers. The usually secretive race was laid bare in the episodes and the tense negotiations have lofty implications for the future of the Federation. Despite all that, the biggest selling point of the two-part story is the return of Leonard Nimoy as Spock. The veteran actor plays the character with an interesting grace that is indicative of 80 years of aging since The Original Series.
Time's Arrow Part 1 & 2 - 8.4/8.2
Time travel has been a part of Star Trek since the beginning, and few episodes had as much fun with the concept as the two-parter "Time's Arrow". While investigating an archeological site on earth, the Enterprise crew discovers that there is evidence that an alien race may have been on earth in the 1800s. When Data is sent back in time to the turn of the century, the crew must attempt to rescue him, as well as get to the bottom of the alien menace.
The most memorable part of the episodes is the appearance from famous author Mark Twain, but there is a lot more to the episodes than simple fan service. The story does a great job of playing with the difficult concepts of time travel, and it explores timelines through the mysterious bartender Guinan. Eventually destined to meet, Whoopi Goldberg excels at playing a younger, and slightly less wise version of her character, centuries before she encounters Jean-Luc Picard.
Redemption Part 1 & 2 - 8.4/8.4
Proving to be the perfect fodder for two-part episodes, "Redemption" brings together both the Klingons and Romulans for one of the most tense stories in the series. Worf's allegiances are put to the test when the Klingon empire descends into bloody civil war. Deciding to leave the Federation behind, Worf goes off to fight for his family name. Meanwhile, Captain Picard unravels a Romulan plot that may be at the heart of the entire conflict.
Worf's emotional journey throughout the story is gripping, and it was genuinely shocking to see him turn his back on the Federation. As always, the dastardly Romulans prove to be tricky adversaries and it is ultimately Picard's insistence on peace that saves the day. As the name implies, Worf is out for a measure of redemption, and he earns some respect within his community because of his selflessness.
Chain Of Command Part 1 & 2 - 8.3/8.9
Fleshing out the ruthless Cardassians, "Chain of Command" was one of the darkest storylines in Trek history and challenged Captain Picard like never before. Sent on a top-secret mission into Cardassian space, Captain Picard is replaced on the Enterprise with a humorless and unpopular fill-in named Jellico. Picard is captured and tortured, while Jellico attempts to stop a full-scale Cardassian invasion of Federation space.
Showing the guileless Cardassians at their most evil, the episodes prepare viewers for what to expect in Deep Space Nine. As for the story itself, Picard's journey is harrowing, and it is interesting to see the ship's dynamic when the beloved captain is replaced by an inferior substitute. Jellico is a fascinating (if unlikable) character, and shows that Starfleet doesn't always produce the best and brightest.
Best Of Both Worlds Part 1 & 2 - 9.3/9.2
"Best of Both Worlds" goes far beyond simply being a great two-part episode, and it shines as one of the best episodes of The Next Generation, and all of Trek in general. When responding to a distress call at the outer reaches of Federation space, the Enterprise encounters a decimated colony that has apparently been destroyed by the Borg. When Picard is assimilated, Riker and the rest of the crew must find a way to save their captain and defeat the Borg menace.
The episodes deftly weave together several narrative threads that pay off brilliantly throughout the two parts. Riker is tempted by the call of higher command, while Picard's strategic mind is brought into the Borg collective which makes them doubly dangerous. While not the introduction of the Borg in the series, "Best of Both Worlds" really established them as the biggest baddie in all of the Star Trek universe.