The Thief and His Master

A father wanted his son to learn something that would be advantageous for him. And so he decided that theft would be a great trade. He sent his son to a master thief and they agreed that if the father recognized his son after an year, he would not have to pay. The father came up a plan, he and his son managed to trick the master thief and they slipped to pay. The thief is however not a stupid man so he knows very well how to get his revenge.