The story concerns Charles, a fifteen-year-old boy who is suffering from a severe illness. The local doctor diagnoses it as scarlet fever, but Charles protests that his hand has "changed" and is no longer under his control. He claims that he has been infected by microbes that are not only causing illness, but literally taking over his body and forming a new being. The doctor, however, assures Charles's parents that this is all in his imagination—a fever dream brought on by his illness.