I think you have the bones of a good story here, but you need to focus more on dramatic moments and descriptive action over exposition. You tell us constantly how strong and intelligent Lyra is, but you never demonstrate it through her actions or specific exploits, and you leave it vague as to what faction she's a part of. This story would do great with more specificity behind it - expanding on the moment of betrayal (as mentioned by another commenter) would be a great opportunity!