Crescendo is a 1970 British horror psychological thriller film directed by Alan Gibson and starring Stefanie Powers, James Olson, Margaretta Scott, Jane Lapotaire and Joss Ackland.

Drawn to the spectacular south of France to research the late composer Henry Ryman, music student Susan Roberts encounters his son, drug-addicted Georges and his eccentric family.

Investigating the haunting strains of an unfinished Ryman concerto leads Susan to discover an empty piano and a brutally savaged mannequin.

Given a plot somewhere between Fanatic [1965] and Taste of Fear [1961], director Alan Gibson has injected a gratuitous amount of sex into the story but otherwise presents the usual mixture with a sure style and a good eye for colour.

Jane Lapotaire overacts rather gratingly as the maid, but Margaretta Scott moves from sanity to insanity with gracious ease, and Stephanie Powers is an attractive heroine, though the thesis never gets very far.