Thelma Tompkins is a waitress in a hotel restaurant. She's a good waitress and has always been kind to old Mrs. Mannerheim who eats in the restaurant every evening. Thelma is shocked when Mrs. Mannerheim tells her that she is her closest friend and has left her a considerable legacy in her will. In the interim, she gives Thelma a brooch. Over the following months, Mrs. Mannerheim becomes ever more demanding and Thelma's musician boyfriend Arthur suggests that maybe the time has come for the old lady's demise to accelerated somewhat. Thelma poison's her tea but without any obvious effect. Thelma takes matters into her own hands and the subsequent coroner's inquiry reveals some interesting information about the poison she was using.