内容简介：
When successful neurosurgeon John MacAndrew performs a routine operation, the patient undergoes a severe personality change post-surgery. Hartman's tumor is diagnosed, a rare condition that leaves its victims deranged and destined to be confined to mental institutions. Blamed by the patient's husband for the dreadful outcome, MacAndrew retreats to his native Scotland to lick his wounds. It is there that he makes new discoveries about the mysterious illness and the chemical that induces it. Armed with this new knowledge, MacAndrew thinks he may be able to save his patient, until he discovers someone is deliberately using the chemical to regress selected individuals and gain eyewitness accounts of events in the past.