This would have been four stars if I'd never finished it. Gail and Diane were good characters and the reader is definitely rooting for them. The escape scenes were well done and the tension high.
The end made the story fall flat, in my opinion. I found it hard to believe that Tom never breathed a word to Gail (who obviously was screwed over by a vindictive judge. However, it's not unusual for women to get harsher sentences for the same crime. A "Boys will be boys" mentality? Not sure), never wrote to her, never got a message to her, but suddenly reappeared AND took the fall to let her and Diane escape? Romantic, but not feasible.
We never learned who had been ratting the women out throughout their escape. The ball was completely dropped, and it's hard to understand how no one in the editing process caught this.
Diane might be innocent, and everyone might know it, but she still was sentenced to prison and she escaped. She is not simply going to walk. It's not that easy to vacate a sentence and give a wrongfully convicted person her freedom. This ending was too glib and easy and disappointed me.
The author gets points for fooling me. I did not figure out who had framed her--at least not both parties. My money was on someone else completely, who turned out to be innocent.