A Killer Slips Away

Lily and Alonzo knock on Anna Mae's door. They've come to take their elderly sister shopping. Instead, her door flies open and a young woman runs past them - covered in blood. Alonzo tries to grab her but she literally slips through his fingers. Inside, they find Anna Mae dead on the floor. Who was this mysterious young woman? Why did she kill an innocent senior? And what does it all have to do with a jar of mayonnaise?