In the wilderness north of Rat Portage in Northwestern Ontario, two Scotsmen – divinity student Simpson and his uncle, Dr. Cathcart, an author of a book on collective hallucination – are on a moose-hunting trip with guides Hank Davis and the wilderness-loving French "Canuck", Joseph Défago.

While their Indian cook, Punk, stays to tend the main camp, the others split up into two hunting-parties; Dr. Cathcart goes with Hank, while Défago guides Simpson in a canoe down the river to explore the vast territory beyond.