Roy MacGregor grew up in Huntsville, close to his beloved Algonquin Park, where he spent his childhood surrounded by stories of the famous painter. At the heart of it all was MacGregor's relative, Winnie Trainor, the "old maid" too eccentric to be considered a romantic character, even if it was well known that Tom Thomson had once been in love with her. MacGregor's fascination with the mysterious painter went deeper. Thomson had made friends in Northern Ontario, but also enemies. He liked to drink and canoe for days on end; he was also seen as a seducer. Be that as it may, the artist's body was found in Canoe Lake in July 1917.

The confusion surrounding his death and burial site was never resolved. In Northern Light (L'étoile du nord), MacGregor offers new leads and reveals previously hidden details of Thomson's final days, as well as forensic data. Was Thomson a good-for-nothing womanizer or a visionary artist and gentleman? Did he drown accidentally or was he a victim of homicide? The myth of Tom Thomson has grown to obscure the reality of what happened, but the answers to many of these questions are finally revealed here.