Killer Nun (1979) on Netflix

Legendary Swedish sex bomb Anita Ekberg stars as Sister Gertrude, a cruel nun who discovers depraved pleasure in a frenzy of drug addiction, sexual degradation and sadistic murder.

A demented nun sliding through morphine addiction into madness, whilst presiding over a regime of lesbianism, torture and death. Sister Gertrude is the head nurse/nun in a general hospital, whose increasingly psychotic behavior endangers the staff and patients around her.

—Arthur Workman <arthur49@user1.channel1.com>

Suffering from chronic migraines, traumatised Sister Gertrude secretly relies on potent morphine injections to keep performing her duties at a hospice. However, as excruciating pain evolves into a daily nightmare, defenceless and unsuspecting patients start dropping like flies, and Sister Gertrude's constant anguish transforms into something inexplicable. Undoubtedly, someone takes great pleasure in inflicting pain on the hospital's elderly inpatients. Is there an escape from the clutches of the depraved killer nun?

—Nick Riganas