This odd piece is often touted as a giallo movie but there's no police investigation, no unknown black glove wearing killer. Instead it's a tale of a beautiful young paranoid woman (played well by Mimsy Farmer) who starts to hallucinate & people around her start to die. Rosemary's Baby and Repulsion spring to mind. As is typical of Italian movies of this time it's brutal, looks beautiful and comes with a great soundtrack.
This film is notorious for having an ending that is as bizarre as it is gruesome. I'm not going to give anything away, other than perhaps it's one of those films where it's left to the viewer to make up his/her own mind what it's all about. I'll certainly be watching this again.