Fort McKenzie prospector Pop Kellogg, just before the arrival of his newly-orphaned grandson Billy, is killed by McBeau and Dawson, who seek the map showing Pop's secret oil claim. Billy, the now newly-doubled-orphaned grandson, is being escorted to Fort McKenzie by Corporal Rod Webb of the Canadian Mounties and his Wonder Dog, Chinook. Webb turns Billy over to the keeping of Anne DuMere, who runs the trading post for Dan Morgan. After several attempts on his life, Rod and Ann manage to link Morgan and a mineralogist, Kincaid, to the LeBeau/Dawson gang, which is now minus Dawson who has been knocked over a cliff to his death by Chinook.