The Blood Sister finale
This M.S. is the nun who'd saved the Vice-M.S. who'd saved Blood Sister, meaning, ironically, that the evidence Blood Sister needs to prove that her salvation-debt really was discharged is also evidence inimical to the legal interests of the tough nun to whom Blood Sister's own saviour is obligated, so Blood Sister gets increasingly tortured and ill-tempered as evidence of the Mother Superior's guilt accretes.
Context
Hal watching JOI's Blood Sister: One Tough Nun: the plot is a chain of salvation-debts — each nun saved by a nun saved by a nun — that closes into a loop when the chain's origin turns out to be rotten. Recovery's sponsorship chain, bent into a circle and weaponized, inside a film by the man who invented annulation.