A blockbuster, six-hour stage adaptation of the classic novel lives up to the hype through deft use of music. I hate to admit it, but I was skeptical. When Hannah Moscovitch—one of Canadian theatre’s brightest-glittering luminaries—told me that her two-part, six-hour adaptation of the classic novel Fall On Your Knees was stuffed with songs, I couldn’t picture how this story could swing into musical territory: Ann-Marie MacDonald’s opus about the Piper family begins with the bleak beauty of an isolated life in Cape Breton’s highlands, pulsing with loneliness before it careens off a cliff into the really bad, really sad stuff—like domestic violence (and worse)…