A Dark Song (2016)

Just finished this and haven’t been this scared by a film in a long time. Definitely give it a shot if you are into the supernatural and the occult.

Written and directed by Liam Gavin, who directed a couple of episodes of The Haunting of Bly Manor. I was gripped throughout

Spoiler free plot synopsis - A woman locks her self away in a remote Welsh house with an occultist in order to perform a dangerous ritual to grant her a desire.

ETA: Thank you to all the dread heads for the related movie recommendations!