Coco had accidentally used forbidden magic while trying to do magic, she was an outsider so she wasn’t allowed to do magic. Only those chosen to be witches or those born witches can do it but Coco saw one do it and figured it out. The spell she had drew freezed the house and everyone in it including her mom, luckily enough Qifrey, a new by witch had saved Cock before it could freeze her. However it had freezed her mom. After learning the spell she used was from a book that could be linked to the Brimmed Caps (witch’s who used forbidden magic and are tracked down by the government), Qifrey decides to take Coco as his apprentice to use her as a lead on the Brimmed Hats and so Coco can figure out how to save her mom. Eventually Coco was able to free her mom from the spell however her mom doesn’t know what happened or that it was forbidden magic or what happened afterwards since she was frozen.