Father Frank Dowling, a fine Catholic parish priest in Chicago, drives housekeeper Marie to despair by his habit of being late for dinner as he and his assistant (streetwise nun Stephanie 'Steve' Oskowski) solve numerous neighborhood crimes, usually involving at least one murder. They generally outsmart the police as well as the criminals. The live-in priest Father Philip Prestwick, whose priority is his own ecclesiastical career prospects, takes a very dim view of their crime fighting and on Sister Steve even being there.