Tomasi Manda, an intelligent boy whose rational mind rejects belief in witchcraft, does something that causes his mother and elder brother to fear that he might be bewitched. They decide to put "protective medicine" into his blood. But their problem is how to get Tomasi to accept the medicine, having once before failed to convince him to have such protection. However, when Tomasi passes his primary school examinations and is selected for a boarding secondary school away from home, the two approach him with the medicine disguised as a charm, something that would bring him good luck from the strangers among whom he will now be living. Tomasi initially rejects the offer, but when, to his surprise, he sees that this causes his mother great pain, he lets her insert into his blood "the totally useless powder." Then certain things begin to happen to Tomasi which, unable to explain them otherwise, he can't help thinking are being caused by the potion his mother has put in his blood. Eventually he becomes convinced that he now has a potent luck charm in his body, and reaches the frightening conclusion that from now on his life will be run by this charm. What is he to do?