When an American graduate student travels France to research a recently deceased composer, her innocent academic project becomes a deadly nightmare that reaches a terrifying Crescendo. The composer's death has caused his widow (Margaretta Scott) to suffer a psychotic dementia, and when Susan Roberts (Stefanie Powers) arrives to study the late master, her arrival triggers an obsessive desire by the widow to ensure that her husband's genius will pass on to future generations...by marrying her crippled son to the American girl. Now, when Susan finds the composer's insane twin (James Olson) living in the attic, her desperate attempt to escape becomes an exercise in pure horror.
