I'm currently writing a story consisting of a mash-up of several fairy tales, with the obligatory TG twist. Courtesy of death threats made shortly after birth, the protagonist (currently about 6 years old) is prohibited from leaving the (small) castle where (s)he lives. However, at some point before the teenage years start, she will need to leave the castle so various assassination attempts (all of which will, of course, be unsuccessful) can take place.

As she has two slightly older step-sisters and an older brother (an arrogant bully called Mohajit, incidentally... translate it and you'll get the joke), step-mum suddenly saying "Can you run an errand to the house on the other side of the woods outside town - and here's a red shawl to wear" out of the blue doesn't exactly cut it, while asking one of the palace guard to kill their youngest child would be ever-so-slightly out of character for someone who to date has only scared the child by glaring at her while keeping annoyance / anger under control.

Needless to say, by the time she does reach 18, she'll have been nicknamed "ash-slut", attended a ball, been poisoned at least once, and fallen into at least one temporary coma (which will probably be of the order of a hundred days, rather than years - putting the entire castle in suspended animation for that long would require seriously large amounts of magic!)

[EDIT]

D'oh! I wasn't very clear on what I needed help with. At the moment, the protagonist is confined to the castle while they grow up, due to a threat made at their birth that they "won't survive long enough to come of age" by an estranged relative believed to be a witch.

So what I need is some plot device to get her out of the castle and into the town / woods beyond.