Brain surgery al fresco, halfway between Lake Superior and Hudson's Bay, where Calvin Heggie's young son Weesha (one of Cal's nine offspring by two concurrent Indian wives) is felled by a big log in the pre-ambulance days of 1786. Native know-how takes care of Weesha's broken arm--splint of willows and moss--but, when wife #1 Lucky seeks further medical attention by canoe-kidnapping a nebbishy English army surgeon, the diagnosis turns out to be grimmer than anyone might have guessed: haematoma. . . a sure-to-be-fatal blood clot on the brain. Green Dr. Ogilvie refuses even to consider the hole-boring trepan operation--no experience, no instruments--but singleminded Calvin forges the vital ""crown"" device out of household scraps, and Lucky's father, mystical but open-minded Chief Ottawa Walker, makes Ogilvie various offers he can't refuse. The Doc conquers his fear, the Chief conquers his superstition, wife #2 Kitty (Weesha's ma) conquers her hysteria, but will readers conquer their nausea as the operation swings into boring (anything but boring) detail? Some should, because, though this is Knox (Raider Moon, Night of the White Bear) at his least ambitious and most contrived, he paddies his canoes and lights his campfires with less blather and more conviction than most.