Seven children chosen for their "special" potential, including Wesley, are beamed straight out of their classrooms and quarters. The rest of the episode concerns both their own and the Enterprise's efforts to convince the Aldeans that this really isn't a workable solution to their problems, honestly, and to subvert their technological advantage in the meantime.
The Reading Rainbow episode "The Bionic Bunny Show" goes behind the scenes of this particular episode.
Tropes featured in "When the Bough Breaks":
- Apathy Killed the Cat: Wesley discovers that the Aldeans have no interest in learning how their own technology works or how to repair it.
- Artistic License Biology: It's actually a plot point in the following season's "Up the Long Ladder" that a population of only half a dozen people wouldn't have a prayer of forming a viable gene pool. Yet the Aldeans expect just seven children to be enough to repopulate the entire planet in the longer term. Presumably their ludicrously advanced technology has some solution.
- Blue-and-Orange Morality: The Aldeans seem genuinely bewildered as to why the Enterprise crew aren't happy with their terms. As far as they're concerned, it's simple — the Federation will be getting valuable scientific and technological advances from them; surely a few kids are a fair price for that when they can always make more? And the kids are bound to get over their parents when they see the benefits of living on Aldea. They simply can't understand why either the parents or the kids would have a problem with that.
- Didn't Think This Through: The Aldeans staunchly insist that their sterility won't become a problem for the children, but they have no way of knowing that, and they end up being wrong.
- Easily Forgiven: Actually more of a show of character than a plot convenience. The crew had every right to leave in a huff once they got Wesley and the kids back. Instead, they get rid of the radiation leaving them infertile, giving them another chance to create a society, though likely also in the knowledge that this will give them no reason to try their child-snatching plan again in case any other spaceships happen by.
- Everybody Laughs Ending: Played with. Wesley brings one of the children up to the bridge at the end so she can thank Picard for saving her. When she gives him a hug, her Tribble-esque stuffed animal sticks to his back, and the whole bridge crew has to smother their giggles as he orders the Enterprise out of orbit.
- Forgotten Phlebotinum: By the end of the episode, the crew of the Enterprise has access to and effective control over the Aldean's technology, which they promise the Federation will help them learn to better understand. The incredible advances this should have reaped for the Federation itself never happen.
- Freeze-Frame Bonus: Dr. Crusher's rapidly flickering rejected diagnoses for the Aldeans' symptoms include everything from esoteric carcinogens to "bad personal hygiene."
- Humanity Is Advanced: In the opening scene, Harry Jr. is running away from his father Doctor Harry Bernard Sr. because he doesn't want to go back to his class because he hates that teacher and he hates Calculus. According to the older Bernard, "Everyone needs an understanding of basic Calculus whether they want to or not." Harry Jr. is around 8 - 10 years old!
- Humans Are Special: A lesser example than usual, but Troi says that humans are "unusually attached" to their offspring. It's unclear whether Troi is serious or if she's diplomatically trying to stress how much the crew resents the loss of their children to an alien race who just don't seem to get it.
- I'm Not Hungry: Wesley convinces the children to go on a hunger strike to show they don't want to stay.
- Invasion of the Baby Snatchers: A variation, as technically it's the Enterprise crew (and their families) who are the outsiders to the child-napping Aldeans.
- Modern Stasis: The Aldeans have long since abandoned scientific study and rely entirely on the automated technological infrastructure built by their ancestors.
- Screw You, Elves!: Picard is incensed when the Aldeans suggest giving compensation for taking their children.
- Sterility Plague: What the Aldeans are suffering from. The fact that it's being caused by the depletion of their ozone layer means that the children they abduct would fall victim to this as well, making their repopulation efforts entirely futile.
- Stockholm Syndrome: A few of the children are a bit reluctant to leave, especially when the Aldeans awaken their potential for artistic pursuits. As they soon realize though, this isn't quite enough to overcome missing their true families.
- Teleport Interdiction: The Aldeans have a planetary Deflector Shield that they can beam through, but the Enterprise cannot at first. After studying the shield they find a way to slip through it.
- Terminally Dependent Society: The Aldeans have been reliant on their technology — especially the Custodian supercomputer that provides for all their needs — for so long that they have basically forgotten how everything works; all the super-advanced scientific knowledge of their ancestors has more or less been stored in a computer archive somewhere and forgotten about. Even the idea that something might, say, break down and need fixing never occurs to them. It's made more literally terminal by the fact that their technology is actually slowly killing them, a fact that they weren't able to figure out for themselves simply because they've lost the relevant knowledge, yet Dr. Crusher — from the supposedly less-advanced Federation — is able both to identify the problem and the necessary treatment in a matter of days.
- Toxic Phlebotinum: Turns out it's the Aldeans' Deflector Shield and cloaking device that are causing all the trouble, degrading Aldea's ozone layer and exposing the inhabitants to ultraviolet radiation sickness. Beyond being sterile, they're quite close to death before Dr. Crusher is able to treat them and the Enterprise "reseeds" the ozone layer (somehow).