When ponies die, they are trapped. Not in Hell (or tartarus) or in another body. They are trapped within the clutches of the evil witch pony Ternifia. She really hates adult ponies, but she loves foals and dead ones. And she has been stealing the souls of dying ponies since the beginning of time. But now, some trillion years later, she's getting bored of only playing with her dead pony toys. They're all terrified of her, and they keep getting older and older. So she decides to start stealing her other favorite type of ponies; fillies. So she starts foal-napping. At first it's just a random young filly from random cities and towns around Equestria. But then when three foals go missing from Canterlot, and another four in Ponyville, and another three in Manehatten, and many more from all over Equestria, ponies start wondering just what the hay's going on.
Auquamarine is a pony in her prime. The best age she could be. She's happy. She's going to school. Nopony looks twice if she has an extra glass of cider. And then her sisters, triplets, foals, disappear. And in her worry she becomes the prime target for the foal-napper. And she doesn't want to die. And to top it off, she happens to find out the real secret behind the foal-nappers foal-napping. And what will become of her. So she seeks out Twilight Sparkle and her friends for help. And they accept. But do any of them know what they're getting into?...