Guest host: Lee Cowan. We report the latest news on Russia's invasion of Ukraine, while Mo Rocca looks at the history of how Russia has oppressed Ukrainians over the years. Plus: Tracy Smith interviews actor Ryan Reynolds; Rita Braver visits a one-woman exhibition for artist Shirley Woodson; Martha Teichner talks with the partners of a Savannah, Ga., restaurant that serves as common ground to discuss race; David Martin sits down with a 24-year veteran of undercover CIA operations; and Kris Van Cleave digs into a sweet Mardi Gras tradition: King cakes.