One of a gazillion versions of the Bloody Mary tale...
Hundreds of years ago, she lived deep in the forest in a tiny cottage and sold herbal medicines for a living. The townspeople called her Bloody Mary, and said she was a witch. No one dared cross her, though, for fear that their cows would go dry, their food would rot away before winter’s end, their children would get sick, or any number of other terrible things might happen if they angered a witch.
Then the little girls in the village began to disappear, one after the other. Their distraught families searched the woods and all the houses and barns, but there was no sign of the missing girls. A few brave souls even went to Bloody Mary's home in the woods to see if she had taken the girls, but she denied knowing anything about the matter. It seemed to her visitors, however, that her normally old and haggard appearance had changed. She looked younger somehow. They were suspicious, but could find no proof that the witch had taken their children.
One night, the young daughter of the blacksmith got out of bed and walked outside to follow a song no one else could hear. The blacksmith's wife had a toothache and was sitting up in the kitchen that night when her daughter left the house. She yelled for her husband and followed the girl out the door. The blacksmith came running in his nightshirt. Her parents tried to restrain the girl, but she kept breaking away from them and heading towards the woods.
The commotion made by the blacksmith and his wife woke the neighbors, who came to assist the hysterical couple. Suddenly, one of the neighbors noticed a strange light at the edge of the woods. A few others followed him out into the field until they saw Bloody Mary standing near the trees, holding a magic wand that was pointed towards the blacksmith's house. As she conjured her spell upon the blacksmith’s daughter, she failed to notice anything else.
The townsmen grabbed their guns and pitchforks and ran toward the witch. When she finally saw them coming, Bloody Mary broke off her spell and fled back into the woods. One of the men had loaded his gun with silver bullets in case the witch ever came after his own daughter, and now he carefully took aim and shot. The bullet hit Bloody Mary in the back and she fell to the ground. The angry townsmen grabbed her and hauled her back into the field, where they built a huge bonfire and burned her at the stake.
As she burned, Bloody Mary screamed a curse: if anyone mentioned her name aloud before a mirror, she would send her spirit through the mirror to avenge her terrible death. When she was dead, the townspeople went to her cottage and found the unmarked graves of the little girls the wicked witch had murdered to make herself young again.
From that day on, anyone mad enough to chant Bloody Mary's name thirteen times before a darkened mirror will summon the spirit of the witch, who will exact her revenge by tearing their bodies to pieces. These unfortunate souls will then burn in torment as Bloody Mary too was burned.