Taina, as the firstborn child in the family, is charged with the task of carrying the family's offering of food to "La Caridad," to keep the family in the good graces of the monster. She never eats enough, as all the food is parceled out to La Caridad, her working father, and baby brother (who she resents for this). So this time, she eats the food meant for La Caridad, unable to hold back her raging hunger.
That night, Taina is visited by La Caridad in the form of a horrifying soucouyant (bloodsucking hag), who drinks her blood and takes her beloved dog in punishment for eating the food meant for her. La Caridad reminds her that as a woman, and the firstborn, it is her duty to "hold tight to the old ways," and after that night, Taina shoulders her responsibility without a trace of rebellion.