One pony. One trip. One way.

If you knew you were going to die, what would you do with what time you had left? For Stellar Lights, the clock is running down. An unfortunate stroke of fate has left her with a ticking biological time bomb in her chest. Her family is wonderful and loving, but Stella certainly isn't blind --- she can see the distant truth in her husband's eyes and her daughter's hugs --- and she can't bear it any longer.

And then the enigmatic Princess Twilight arrives on her doorstep with a proposition. Stella will undertake an epic journey, so terrifying in scale that no pony has any hope of making it back alive. At the end, the lost destination of Celestia and Luna, whom disappeared from Equestria all those centuries ago. But Stella doesn't have to make it back...

The end she isn't worried about. The journey is all that's left.