The detectives had told the prince that there was no chance of finding the mysterious girl. The prince was very upset and angry until Cinderella called him and explained everything to him. They then set up a scheme no one would see coming.
Their plan all started with the prince showing up telling the step-family that one of the 2 girls will be chosen as the prince's new wife. Soon the girls would start fighting over the prince distracting them, for the next phase of the plan.
Next Cinderella would call the police and the butler would sneak away and free Cinderella. By the time the police arrive the prince will keep up the act.
Finally the police arrived. The step-mother was arrested for child abuse, and the step-sisiters were adopted into other families. They were arrested and the prince took Cinderella back to his palace.
The prince and Cinderella got married and lived happily ever after.