Drinking Habits is a farce in two acts. Sister Augusta and Sister Philamena have been secretly making and selling wine for years to keep the doors of their small convent open. But when their wine suddenly wins an award, newspaper reporters (and former fiancées) Paul and Sally begin searching for the vintners.
As Sally and Paul spy on the convent, they are caught by Mother Superior. Sally pretends to be the new nun Mother Superior was expecting, and Paul claims to be a visiting priest. But when Father Chenille sees Paul, he suspects Rome of sending out a new priest to replace him. And when the actual new nun, Sister Mary Catherine, does arrive, Mother Superior believes her to be a spy from Rome, sent out to investigate the convent.
Chaos ensues as Augusta and Philamena try to secretly press more wine, Paul and Sally try to find the winemakers, and Mother Superior and Father Chenille spy on the suspected spies.