Synopsis:
In this episode, Worf catch up his step-brother Nikolai, he is with an alien race who is gonna be extinct after some natural events who gonna erase the life of that entire planet.
But Nikolai do has another plan; transport all the people while they are sleeping into the holodeck and make them believe they are still on that planet, find another world were this race can live and simulate with the holodeck to just travel away from they town, into a uncharted place.
Important: This race is setted on dark ages, so they don't really know about space ships, or even Nikolai is an human, so he is an alien between them.
Review:
In the entire episode we see why save that people is complicated, but not impossible.
1) What if they find out that is a simulation? Imagine get out of your house and then finding out that is a holodeck and you are in an alien planet, imagine knowing you were."kidnapped" without even know about it.
2) Finding a similar planet is not that easy.
3) The holodeck has troubles to hold on the simulator for so long since the Enterprise was affected before leave the planet.
4) You can't really garantee their future, you cannot simple play as a god.
In this episode this things are discussed and in the worst of cases; we see the consecuences.
It's a matter of moral and ethical thing to do or not to do, the Prime Directive was already a topic in the series and they do it again, and that is what make this series so interesting, is not just spaceship fighting, is about resolve problems, know what to do in a future who we can be those "aliens who come in peace", not for nothing the diplomacy is important for interact with other races who already reach the space travel age.