Sophie Hatter has a boring life, and is almost sure she wants it that way. Then the Witch of the Waste casts a spell on her and turns her into an old woman. Sophie decides to hobble out and seek her fortune. She makes a pact with Calcifer the fire demon and enters into the service of the Wizard Howl. He eats girls' hearts, but Sophie's not worried since she's no longer a girl. Soon Sophie must save Calcifer and Howl from a bargain that helps neither,
What bargain that helps neither?
save her younger sister from Howl's heartless courtship, and save the Kingdom of Ingary from the Witch. Sophie learns that she's not as timid as she thought, she has an incredible talent for magic, that she's not immune to the Wizard's charms, and that in Ingary, even the oldest of three can live happily ever after.
Oldest of three? What?
This is mostly well done, and I might be intrigued enough to request this. But this highlights a common difficulty in writing a synopsis-- forgetting what elements will be confusing/meaningless to someone who hasn't read the book.