Review: ‘The Underground Railroad’ conducts an unsettling ride through an alternate history

"The Underground Railroad" has an almost dreamlike quality, exploring an alternate history of the antebellum South that filters Colson Whitehead's Pulitzer Prize-winning book through "Moonlight" director Barry Jenkins' lens. But the emotional wallop delivered by Amazon's beautifully rendered limited series is somewhat offset by the journey's length, stretching about six terrific hours' worth of TV over a 10-hour format.