Billie's best friend says Ms. Marble has a hundred cats in her apartment and sings to them all day long. But when Billie spends an afternoon with her elderly neighbor, she discovers that Ms. Marble is actually a lot of fun! Ms. Marble introduces Billie to Lady Day, Bessie Smith, and other great blues singers. Together they dress up in vintage clothes and dance to the blues. Then Ms. Marble shares an old secret she has been keeping in her heart. Billie learns that "some hurts stay inside you a mighty long time," but Ms. Marble assures her young friend that "the sun's gonna shine in my back door someday.