Guest host: Seth Doane. In our cover story, Tracy Smith looks at the tragedy of postpartum depression, and a promising new treatment. Also: Robert Costa interviews former House Speaker Kevin McCarthy, who this week announced his retirement from Congress; Ted Koppel looks at how black lung disease is worsening among ever-younger coal miners; Seth Doane visits the artists at Aardman Animations, makers of the stop-motion feature, “Chicken Run: Dawn of the Nugget”; Jonathan Vigliotti reports on the rebirth of a pop art amusement park, Luna Luna, which debuted in Germany in 1987 and then disappeared; David Pogue (sorry, “Techno Claus”) shares his gift ideas for the gadget lovers on your holiday list; and we look back on the lives of legendary producer Norman Lear and Oscar-nominated actor Ryan O’Neal.