The Enterprise is on a routine science mission, studying protostars in the Volterra Nebula, when Picard receives a puzzling invitation to the observation lounge from Riker. Entering to see a statuette highlighted on the table, Riker brings the lights up to reveal a guest, Professor Galen, Picard's old mentor from his days as a xenoarchaeology student. The captain is overjoyed at this surprise visit. After they exchange heartfelt greetings, he eagerly resumes the role of pupil as Galen quizzes him on the Kurlan naiskos, a gift from his recent explorations, sitting on the table. Picard gushes over the extraordinarily rare find.
The conversation turns serious as Galen teases Picard about some new research he has been doing over the past decade, an impending discovery that he claims will shake the galactic community to its core. But he won't say any more unless Picard agrees to accompany him on his archeological adventure. It would mean giving up his command, however, and Picard can't bring himself to do that, no matter how tempting the adventure. The professor is personally affronted at being refused — again — by his favorite student, throwing back several cutting invectives before storming back to his shuttle.
Some days later, the Enterprise receives a distress call from Galen's shuttle, which has been boarded by a hostile Yridian ship. Picard orders it disabled, but the Enterprise's phaser blast destroys it completely. Galen, mortally wounded by a disruptor, is beamed to sickbay. He only manages to say "I was too harsh," before dying.
With both Galen and his attackers dead, the crew have only the shuttle's computers to shed light on what happened. What little data they can retrieve, a series of numbers, is presumably part of Galen's mysterious research and what the Yridians were after, but means nothing to them without further context. A new clue emerges at Galen's intended destination, Indri VIII, which has just been scoured of all life. With the presumption that Galen's research is biological in nature, the computer identifies the data as an assortment of ancient DNA fragments from across the quadrant. Such disparate fragments should have no relation to each other, but Crusher notes that they have similar protein configurations. They connect to form an algorithm that could only have been deliberately engineered four billion years ago.
They must find the missing fragments to discover the purpose of the program. It seems they are out of leads, until Picard remembers that Galen acquired his naiskos from the Kurlan system. The only life-bearing planet there, Loren III, is not among the DNA fragments, possibly stolen by the Yridians.
The Enterprise arrives to find not one, but two interested parties: the Cardassians and the Klingons, neither of whom are interested in sharing what they are convinced will be some cool ancient technology. Picard convinces the captains, Gul Ocett and Captain Nu'Daq, to see reason. If they don't cooperate, no one will find all the pieces. As luck would have it, there is only one piece missing between the three of them, so they have the computer search for it by analyzing the existing fragments for a pattern.
As soon as it spits out the result, Gul Ocett turns on them. She retreats to her ships, disables her erstwhile allies, and takes off towards Rahm-Izad.
Which is the wrong system. Ocett apparently made a botched attempt to subvert the Enterprise's defenses, so Picard and Nu'Daq were prepared for her betrayal and decided to turn the tables by giving her a false lead. Nu'Daq's ship was still damaged during the ruse, so he is forced to remain on the Enterprise.
Their real destination is the Vilmoran system, where they find one planet with trace amounts of organic lichen that promises to be the final piece. On the surface, the crew (plus Nu'Daq) are soon joined by a very annoyed Gul Ocett... and a party of Romulans, whose cloaked ship has been tailing them from the start. A Mexican Standoff ensues. While everyone is busy bickering over who gets the prize, Picard and Crusher surreptitiously scrape some fossilized residue into a container. Their tricorder puts the last piece into place, and then...
A recording plays from one of the billions-old race that created the puzzle. She gives a heartfelt (and somewhat ironic) speech congratulating them for coming together in a spirit of friendship to find their secret message, explaining how the various humanoids across the quadrant were seeded by them eons ago. The audience, apart from Starfleet, is clearly not pleased by their reward and go right back to insulting each other as they leave.
It is a bittersweet conclusion for Picard. The discovery his friend had sacrificed so much for, including his life, has fallen on deaf ears. That is, until he receives a message from the Romulan commander, who says something rather unexpected in parting.
Romulan: Well then, perhaps... one day.
Picard: One day.
- Absent Aliens: Billions of years ago, the precursors realized they were alone in their section of the galaxy, so they created all the Rubber-Forehead Aliens in their own image.
- Apocalypse How: The Klingons trigger a Class 6 on Indri VIII.
- Benevolent Precursors: The precursor aliens seeded life on multiple planets and left scattered clues hoping it would make the younger races work together.
- Big "SHUT UP!": Picard has to yell at the Klingon and Cardassian captains to make them stop arguing."mevyap! Enough!"
- Big "WHAT?!": Nu'Daq, when his incompetent Number Two is unprepared for the Cardassians' attack.
- Bittersweet Ending: Picard finishes Galen's work, but the Klingons and Cardassians completely ignore the lesson it teaches. The Romulans, on the other hand, are more receptive.
- Bribe Backfire: Nu'Daq tries to subtly bribe Data, who immediately calls him on it.
- Curb-Stomp Battle: The Cardassians think they pull one on the Enterprise, but Picard is ready for it.
- Death Equals Redemption: Galen apologizes for being harsh to Picard on his deathbed.
- Early Installment Weirdness: This is the only appearance of a female Gul in the Cardassian military. It's later established that there's a gender divide among Cardassian society, where men dominate the military and women the sciences.
- Either "World Domination", or Something About Bananas: A non-linguistic variant—Nu'Daq and Gul Ocett argue over whether the genetic program is a weapon, a power source, or a recipe for biscuits.
- Famous, Famous, Fictional: As two examples of historically famous archaeologic discoveries, Galen mentions the city of Troy on Earth and an undescribed alien location called Ya'Seem.
- Feed the Mole: When Geordi discovers the Cardassians' attempt to sabotage the Enterprise's Deflector Shields, Picard arranges for them to be given false information as to the whereabouts of the final genetic piece, and then has the Enterprise prepared to minimize the damage from the sabotage.
- Mexican Standoff: Involving the Klingons, Romulans, and Cardassians. Picard and Crusher put an end to it when they collect the final DNA sample and finish the program.
- Never Give the Captain a Straight Answer: Riker summons Picard to the lounge, and La Forge summons him to engineering.
- No Delays for the Wicked: Despite being given a false lead, Gul Ocett manages to make it to the Vilmoran system only a few minutes late for the final confrontation.
- No-Sell: Data completely tanks the headbutt that the Klingon captain gave him in anger after thoroughly trouncing him at Klingon arm-wrestling. And then politely explains the technical details as to why he was completely unfazed by the assault.Data: My upper spinal column is a poly-alloy, designed to withstand extreme stress. My skull is comprised of cortenide and duranium.
- Not So Different: The Romulan commander acknowledges this between his people and humans.
- One-Sided Arm-Wrestling: Nu'Daq challenges Data to B'aht Qul (Klingon arm wrestling). Data wins in .47 seconds.
- OOC Is Serious Business: It's the captain from the xenophobic and isolationist Romulans who's most impacted by the message, showing that there is hope for the galaxy after all.
- Panspermia: The precursors seeded life on Earth and most other inhabited planets.
- Pardon My Klingon: Nu'Daq does this a lot. So does Picard at one point.
- Planet of Hats: Picard explicitly says the Yridians are information dealers.
- "Ray of Hope" Ending: Downplayed, as the conclusion isn't entirely a downer to begin with, but Picard's disappointment is tempered by a brief but receptive message from the Romulan captain at the very end.
- "The Reason You Suck" Speech: Professor Galen gives Picard one for staying on the Enterprise instead of joining him. It turns into Parting Words Regret when Galen is killed by the Yridians.
- Rubber-Forehead Aliens: The episode is basically a giant excuse for the Trek franchise's multitudes of aliens who all look more or less the same except for their rubber foreheads.
- Screw the Rules, I'm Doing What's Right!: Picard blows off a Peace Conference to finish Galen's work.
- Survivor's Guilt: Picard briefly feels it for not going with Galen. Troi sets him straight.
- Unwitting Pawn: The other crews to the Romulans, who simply sat back under cloak and let them do all the hard work.
- Wide-Eyed Idealist: Though personally touched by the precursor's lesson and what it means for Galen's own legacy, Picard regrets it all fell on deaf ears, but Beverly suggests that may change one day. The Romulan captain then validates such a belief.
- The Worf Effect: It's a different Klingon this time, but Nu'Daq shows us just how physically superior Data is. Data immediately trounces him in arm-wrestling with no apparent effort whatsoever, then he tries a head-butt only to be somehow thrown back a few feet while Data doesn't even flinch.
- Worthless Treasure Twist: The result of the episode-long chase isn't a weapon or a power source, but a message from the beings responsible for humans and humanoid aliens. The Klingons and the Cardassians are not pleased.
- "Yes"/"No" Answer Interpretation: When Picard tells Nu'Daq and Ocett that he knows they're both trying to complete Galen's genetic research, neither one of them says anything, which Picard takes as a confirmation.