After an ill-fated bank robbery, a couple of petty criminals end up with two suitcases of stolen cash and an assortment of angry thugs -- including their boss, a vicious London mobster -- on their tails. They decide to hide out in a convent school disguised as nuns -- and they do so with the blessing of one very practical and hard-nosed Sister Superior who hopes to refill the convent's shrunken coffers with some of the cash from their suitcases.