Trapped And Freed

When a 16 year old girl is found and saved from her father, officers Liam and Lexi decide to take her in, and help teach her things.
Having a kid in their house who can't talk, read, and write is not easy, but they don't give up.
But one question remains, who is this mysterious girl?
And what happens when Liam decides to run tests on her one day?
What do lexi and Ava do when they find out about the secrets Liam's hiding?