 Morgan is a witch, but a good one, and she doesn t want her son Arthur to become a sorcerer of evil like her cousin Molock. That s why she plans to take his powers from him with a special ceremony. For that she needs the help of a  godfather  : Mr Firth, who has the same birth date as the baby, and who is an inventor of genius. So she bewitches him and go with him to her grand-mother s, who explains her the godfather will become dumb after the ceremony. But Mr Firth truly loves her and she s reluctant to use him. They go to Venice, where she tells him she s a witch. Molock finds them and try to kill Mr Firth. To stop him, Morgan has to promise she ll give him an heir...