I haven't read that book, but I have read many thesis statements from hundreds of students. I've also had to write my fair share. Your thesis is fine. I can help you tighten it up a bit, so that it flows better and clearly announces your purpose.
One reason that I like your thesis is because you have made a statement of opinion -- the children mature quickly because of their situation. Great thesis statements always express a defensible opinion. Your statement also tells your reader that you plan on using characters from Stratton's book. All good stuff. Nice work.
My main concern about your thesis is that it is overly "wordy" in places. It doesn't flow as smoothly as it could. You could try it this way:
Chand's Secrets by Allan Stratton shows that children mature more quickly, when they are forced into serious situations.
Your original thesis is still present. I simply cleaned it up a tiny bit. Good luck!
I love it! Thank you so much! :)