The Enterprise is on its way to pick up some virulent specimens of various pathogens, for which the newly-minted Chief Engineer Geordi La Forge has designed a biohazard containment module. Dr. Crusher has left for a post with Starfleet Medical, and the new Chief Medical Officer, Katherine Pulaski, has failed to report to Captain Picard on schedule, opting to visit with Counselor Deanna Troi in the ship's lounge, Ten-Forward, instead. Picard is preparing to chew Pulaski out for this when Troi makes a startling announcement: she is pregnant.
The senior officers gather to discuss the development. Riker is both surprised and annoyed, and says, "I don't want to sound indelicate, but who's the father?" It turns out something that Deanna can only describe as a "presence" entered her body and took up residence in her womb. It's the fastest progressing pregnancy Dr. Pulaski has ever seen; the fetus is apparently twelve weeks along after eleven hours. Worf thinks whatever's growing inside Counselor Troi is probably a threat to the ship and suggests abortion, while Data thinks they should study it. The Counselor shuts them all up with, "Do what you have to in order to protect the ship, but know this. I'm going to have this baby."
Before the Enterprise commences loading its extremely dangerous cargo, Dr. Pulaski and Data catalog the specimens together. Pulaski calls Data "Dah-tuh" and Data informs her his name is pronounced "Day-tuh". When she asks what the difference is, he replies that one is his name, the other is not. Pulaski also remarks that the pathogens are a result of some "eager beaver at play." Data doesn't understand, so Pulaski explains that some scientist used genetic engineering just to see how bad bad could get. They inform the Captain that if the most innocuous of the pathogens gets loose, it'll destroy all life on the Enterprise in a matter of hours.
Meanwhile Troi has her baby that same day, and reports no pain during delivery. It's a boy! He is named Ian, after Troi's father. Picard decides to visit the child at Troi's quarters a while later and the boy has the appearance of a toddler. He tells the astonished Captain, "Don't worry, everything will be alright."
Later, Ian has the appearance of a preteen, and when Picard asks him why he's there, he responds that it's dinnertime. Picard says, "No, why are you on this ship?" and Ian responds that he's not ready to reveal that yet.
La Forge starts noticing that some of the pathogens are starting to multiply for some reason, which they should not be. If they continue to multiply, they will burst through containment.
Ian tells Troi that he has to leave now, or it will be very bad for everyone. He then gets really sick and dies. Troi is saddened, but after Ian passes away, the body disappears and a sparkly ball of light floats up and settles in Deanna's cupped hands. She says he was curious about them and wanted to learn more about them. It turns out the entity was giving off some energy that was encouraging the pathogens to grow, and that he left in order to save them.
This episode provides examples of:
- Answer Cut: The crew is listing possible sources of the radiation that's causing the pathogens to grow. After rejecting two possibilities, Dr. Pulaski says that something on board must be the cause. Cut to Ian, being tucked into bed.
- Artistic License Biology: If the child really was identical to Deanna, it should have been a girl.
- Badass Beard: This episode marks the first appearance of Riker's trope-naming beard.
- Dead Guy Junior: Troi names Ian after her dead father.
- Energy Being: The ball of purplish white light that impregnates Troi.
- Establishing Character Moment: The first thing Dr. Pulaski does is not report for duty. She's in the bar at the time, talking with Deanna. As Worf says, "Not the best way to meet your captain." Most of the more notable moments she has involve insulting Data repeatedly, even though he can't be insulted, which just comes off as pure spitefulness rather than the ribbing McCoy would give Spock. And she's not even doing it on purpose. She just doesn't think of Data as a "real" person.
- Granted, both have justifications, as Deanna, a patient, has asked to speak with the Chief Medical Officer, apparently in a comfortable setting, as she talks about the pregnancy, while, as we see with the later attitude of Starfleet Command officers in Measure of a Man, even their superiors aren't fully convinced that Data is more than a piece of machinery at this point in time. Still, not the best foot to put forward in her first appearance.
- Everything Fades: Ian dissolves into sparkles after he dies, then reconstitutes himself into his original Spark Fairy form.
- Express Delivery: Troi's pregnancy goes from conception to birth in less than two days.
- Expy: A Chief Medical Officer who argues with the emotionless Bridge officer, and hates transporters. Where have we seen that before?
- Good Girls Avoid Abortion: Worf suggests abortion due to the unusual nature of Troi's pregnancy as a possible threat to the ship, but Troi adamantly refuses.
- Heroic Suicide: Ian wills himself to death in short order once he realizes that he is the source of the danger to the Enterprise.
- Ignored Epiphany: When Pulaski mispronounces Data's name and he corrects her, she speculates that Data taking umbrage at the mispronunciation is an emotional response. Throughout the series Data displays wonder, confusion and surprise (among other things), which are all emotions. But Pulaski is the only character who ever makes this point, and she never mentions it again after this episode.
- It Is Pronounced Tro PAY: The argument between Pulaski and Data over the latter's name pronunciation. Which, incidentally, is the only time in the franchise that anyone brings this up.
- Mythology Gag: The classroom Ian visits has the letters of the Latin alphabet on the wall—in the original series' title font.
- Opposite-Sex Clone: Ian is basically this to Troi—no other DNA besides hers is detected in his genome.
- Plot-Relevant Age-Up: Ian has a vastly accelerated development cycle, going from conception to a lad of 10 in three days.
- Put on a Bus: Dr. Crusher has left for a post as head of Starfleet Medical. Wesley is supposed to join her soon, but decides that he would rather stay.
- Rank Up: Geordi was promoted to full lieutenant along with becoming Chief Engineer.
- Remember the New Guy?: Guinan and Ten-Forward make their debuts in this episode, with the implication that they were on the Enterprise throughout Season 1. Although, in a much later episode, Picard mentions that Guinan joined the ship a year after the Enterprise took off.
- Sense Freak: The day-care teacher notes that Ian loves to touch and examine things; he has a ball playing with and cuddling a litter of puppies. Later, Ian burns himself on his soup just to experience pain.
- Spark Fairy: The Energy Being that becomes Ian is a purplish white flying speck of light.