Martha is a witch at one of the best school there is and only the best students or the rich go there.
She was the top student in the school in everything... except for magic. She sucks at magic and thinks she is just weak but that is where she is wrong. She is actually very powerful but has no idea how to do magic properly and accidentally turns her familiar Eric into a human... ish? She has no idea how to turn him back because no one has done it for decades.
I should probably tell you about the fact that Eric can levitate so don't be surprised about the flying cat.