Tales of the Midwinter Hag describe an immense and voracious creature that appears during the coldest months. Her arrival may be preceded by souring milk, failing hearth-fires or frost forming inside shuttered windows. She rarely approaches a household in her true shape, instead appearing as an old woman in the snow, an injured traveller, a lost child or someone the occupants believe they recognise.

A great cat commonly accompanies her and can disguise itself as a stray or familiar household animal. Their disguises are imperfect. The cat may weigh more than a grown man can lift, while the Hag leaves footprints too deep for her apparent frame.

Once welcomed inside, the cat purrs and draws those nearby toward unnatural sleep. The Hag then sheds her borrowed shape. Old tales say she empties stores, kills livestock and turns upon those who sheltered her. Some settlements therefore leave a guest's portion outside, hoping hospitality offered there allows the stranger to be refused entry without offence.

Those carried away are seldom recovered, though remains found in distant dens have sometimes been recognised by people from different settlements. Parents also use the tale as a warning against disobedience, greed or neglect of old customs, depending on the offence of the week.