In colonial America, frontiersman Major Robert Rogers (Tracy) sets out to blaze a trail through uncharted territory, taking along a mixed bag of callow youths (Robert Young) and grizzled pioneers (Walter Brennan).
In shining 1940 Technicolor, Tracy pits himself against the elements and the injuns, notably in classic fording-the-river and massacring-the-hostiles sequences. Though it seems to be a conventionally heroic (and racist) version of the winning of the West, the vehemence of Tracy's anti-Indian attitudes - one of his men keeps a redskin's head in a bag and eats bits of it - is deliberately disturbing.
It bears the subtitle Book One: Rogers' Rangers because King Vidor intended to film the rest of the hero's life in another film, which explains why the plot never actually gets around to the Northwest Passage.