Film Mad Nun Bell

I'm organazizing my plot notes for M5 and the M4 CE materials (although there's no guarantee of the CE award but we have to be prepared), and compiling a style guide and 'mood and reference' library for my art elves.
I won't give too much away, but we're off to the Alps and there will be snow and ghosts and lots more tears. The mood is also darkening; be prepared for some sinister experiments.

I had a vague recollection of some film I watched years ago - the kind of thing that would nestle snugly into the style guide, like a tapeworm in a kidney. All I could remember was a mad nun ringing a bell high in the mountains.
Name that film!

Here's the denouement.

*** Spoiler alert ***
If you've not seen this film and don't want the climax ruined, either don't watch the vid, or stop it around 4 mins 30 secs.

What an absolutely staggering feat: the nunnery was filmed entirely on set, and at a time when Technicolor was still in its experimental stages.
The sunrise over the mountains - the calm before the storm! Little Joseph tugging Sister Clodagh's sleeve (NVC), failing at first to rouse her from her troubled contemplation. (Little Joseph can even tell the time without consulting his Auntie's watch.) He hands her a drink (a gift), and delivers a little pre-denouement charm and humour. Then into Sister Ruth's pov. She's one crazy nun! Check out the XCU - the red raw skin about her eyes, the sweat, the wet hair. Sister Clodagh heads to the chapel to pray for help. Great dual colour palette! She means business - she rolls up her sleeves. The strain takes its toll and she all but collapses into prayer. Back into pov as we sneak up on her through the door. Are we crazy Ruth again? Clodagh is drenched with sweat. A creaky floorboard - Clodagh looks up; Ruth hurries away. There's a showdown coming! Behind you! Too late - she's gone. Into pov again, watching down over Clodagh as she refreshes herself from blood-red water. It is time! An amazing, languid shot of Clodagh walking along the rain-wet edge of the precipice - any protective walls have been lost; the wind dances in her habit. She steadies herself as she walks alongside the crumbling wall, looking about her. Then, straight from the fires of Hell, Ruth scurries back down the steps. At the bell, on the edge of the world, Clodagh grips the rope and rings... mad eye Ruth flings the door open, her wild hair writhing like Medusan snakes. Clodagh is weak - drained - as she prays for absolution. Too late? Ruth stalks her prey, slows, tenses...

Enjoy!