The Charwoman’s Shadow by Lord Dunsany

Ramon Alonzo apprentices himself to a magician to learn alchemy and create a dowry for his sister. However, Ramon must pay a price for this knowledge. He must give up his shadow.

Despite a warning from the magician’s immortal and shadowless charwoman, Ramon agrees and soon realizes his grave error. In a desperate attempt, he tries to outwit the sorcerer and win back both his own shadow and the charwoman’s, in order to release them from the sorcerer’s grip.