A rich woman who uses meditation to deal with pain is visited by her niece who returns from Paris. The woman can be a handful and one of her employees suggests to her husband that he kill her freeing them both. When an affair starts between the husband and the niece murder becomes a real possibility. However some people won't stay dead.
Acting
Georgina Cookson's magnificent suffering
Costume
Mourning glamour that slays
Direction
Hessler's Hammer-adjacent atmosphere

Director
Gordon Hessler
Trivia, insights & behind the scenes
Also released as 'The Woman Who Wouldn't Die' and 'Candle for the Devil' in some markets—studio clearly couldn't decide if it was horror or thriller.
Gordon Hessler made this between his better-known Poe adaptations for AIP; it's essentially 'What if Corman's gothic women had to do their own scheming?'