Christopher still had one hand on his computer mouse. The screen displayed the prescription he had just written for Cosmo. He glanced from the screen to Cosmo, who was still standing there.

The boy, who had always been polite, suddenly asked, "Dr. Rivers, do you really not remember me or my sister?"

Something in Christopher's mind and heart suddenly jolted. His tone changed as he replied, "What are you talking about?"

Christopher had known Cosmo for a while. After undergoing hypnosis more than two years ago and returning to the hospital, Cosmo started coming to him for medication.

The medication was a new treatment for heart disease developed by the...