The Pyx

The Pyx also known as The Hooker Cult Murders and La Lunule is a 1973 Canadian supernatural thriller film starring Karen Black and Christopher Plummer. It is based on the 1959 book of the same title by Montreal author John Buell.

Filming began on August 24, 1972, and was completed on October 2, 1972. It was filmed in Montreal, Canada, and includes much French dialog, alongside the main dialog in English.

Source: Wikipedia