Investigating primitive radio transmissions detected on a long-range Federation listening post, the Enterprise investigates a planet far in the unexplored border space of the Alpha Quadrant. There, they discover a primitive planet just starting its industrial revolution--a planet complete with extensive lunar colonization and in the process of launching its first warp-capable ship.

The failure of the alien ship initiates first contact--with a race of adorable talking horses. A first contact with some unique diplomatic idiosyncrasies--and hints of a more sinister plot behind the warp-vessel's destruction.

Shortly into starting her well-earned retirement, Celestia begins to develop unusual symptoms. Twilight, Starlight, and Trixie investigate, only to find that the Princess is dying.

And it is not the first time.