Plot: Ted Koppel looks at how artificial intelligence is being developed for the military; Tracy Smith sits down with singer and activist Joan Baez, subject of the new documentary, "Joan Baez I Am a Noise"; Martha Teichner profiles Hernan Diaz, author of the Pulitzer Prize-winning novel "Trust"; Rita Braver talks with the cast of the Broadway revival of Stephen Sondheim's "Merrily We Roll Along"; Rob Costa talks with former Washington Post editor Marty Baron; and Conor Knighton visits forensic scientists who investigate crimes against wildlife.