Walter Mosley has been writing Easy Rawlins detective novels for more than 40 years now. The National Book Award-winning author joins Tom Power to talk about his 17th and latest book in the series, “Gray Dawn: An Easy Rawlins Mystery.” Walter opens up about his beloved character, why he says Easy’s role is to testify about Black history in America, and why this time he’s done something he almost never does: written an introductory author’s note.