As the conclusion of Ken Burns' two-part biography begins, it's 1885 and Mark Twain is celebrated, rich and content. The good times wouldn't last. The money went first ("He was hopeless as a businessman," says Arthur Miller), forcing him on lecture tours and into virtual exile abroad. Then family tragedies left him embittered, toward God, mostly. But his celebrity kept him going, and at his death, on April 21, 1910, he was "the most conspicuous person on the planet," says narrator Keith David.