The girl managed to escape through a combination of her wits and luck. She found a hidden passage and took advantage of a moment of distraction by her captors.
The 'the girl who escaped' could be about a girl who managed to break free from a difficult situation, like escaping from a captor or a bad environment. But without more details, it's hard to say the full story.
I'm not sure specifically who the girl is without more context. It could be a fictional character created for a particular story, perhaps a girl who managed to escape from a difficult situation like a dangerous place or a bad relationship.