Professor G.H. Dorr, a courtly Southern gentleman, arrives at the home of devout, elderly Marva Munson, hoping to rent her extra room and use her basement to rehearse with his classical music ensemble. His fellow musicians, however, are actually criminals, and together they plan to rob a casino. When Mrs. Munson learns of their plan, they decide she must be silenced. Certainly, murdering one little old lady cannot be too difficult.