At the start of the film Sarah tells Toby a story, and it’s a story which seems to become far more familiar as the movie continues. It’s not necessarily a direct echo of her own existence but you can certainly see the parallels between this short story and the rest of the movie as it unfolds.
Once upon a time there was a beautiful young girl, whose stepmother always made her stay home with the baby. And the baby was a spoiled child, and he wanted everything for himself, and the young girl was practically a slave. But what no one knew was that the King of the Goblins had fallen in love with the girl, and he had given her certain powers. So one night, when baby had been particularly cruel to her, she called on the goblins for help.
“Listen” [Comes from the wardrobe]
“Say your right words,” the goblins said, “and we’ll take the baby to the Goblin City and you will be free.”
But the girl knew that the King of the Goblins would keep the baby in his castle forever and ever and ever and turn it into a goblin. So she suffered in silence, until one night when she was tired from a day of housework, and she was hurt by the harsh words of her stepmother, and she could no longer stand it.