Have you ever been trapped?
Not just physically, like in a prison cell, but also emotionally or metally, where someone, or something, imposed control over you. You wanted to get out, but those handcuffs were too tight, that chain too short.
Being trapped is among the recurring themes in Young Adult literature. While it pops up often in general fiction, the theme hits hard and low in teenage fiction, probably because the teenage are often so full of this feeling of being trapped.