A nightclub singer accidently witnesses a murder and is disguised as a nun so she can hide in a nunnery until the time comes to testify.
This is a film of such, if you must, "high concept" that one simply needs to hear the "pitch" to know everything that will inevitably unfold: Whoopi goes into a convent. Yep, that's it. And a thoroughly inane, inoffensive affair it is too - absurd, predictable but not actually inept, and completely dependent upon Whoopi playing it at full throttle.
She is Delons, a third-rate nightclub chanteuse who has Big Hair and keeps company with club owner/hood Vince (Keitel), the kind of guy who gives a girl a purple mink - and it's his wife's. Disenchantment rapidly turns to consternation after Delons sees Vince rub out a squealer, whereupon she sensibly runs to the cops and nonsensically is stashed with the good sisters at St. Katherine's in a witness protection "twist".
Naturally, she drives humourless Mother Superior (Maggie Smith on one grim note) mad, and, naturally, the cute convent inmates comprise one fat, jolly nun, one daffy dear old nun, one timid novice, etc. Since this nunnery also boasts an impossibly bad choir, Deloris takes charge and turns the poor parish into a happening congregation, boogeying down to ditties like My Guy re-addressed to the dude upstairs, though the forces of evil inevitably intrude for a no-surprises-here climax that is never quite as madcap as it would like to be.
Despite its hopeless predictability, this is one of those preposterous and sweet-natured family frolics that you find yourself enjoying in spite of yourself. Check your critical faculties in at the door and get stuck in.