Mary Agnes Thomas was 41 when she was last seen in Quesnel, British Columbia, on September 10, 1971. The circumstances of her disappearance are sparsely documented; there are no known witnesses to her final movements and investigators have described the case as having very few substantive leads.

In the days and weeks after her disappearance, concern grew from private worry to a public search, but over the ensuing decades the trail went cold. The passage of more than fifty years has complicated efforts, with memories fading and potential evidence lost. Her family has been left without closure and the community continues to carry the uncertainty surrounding what happened to her.