The Last Thing She Saw — Nina Laurin

This thrilling and intense psychological novel from the bestselling author of Girl Last Seen follows the residents of a rural town in Quebec as they grapple with long-buried secrets coming to light after the discovery of a child's remains.
 
After a flood destroys the historic center of a small Quebec town, a child's body is discovered. The remains are decades-old and nearly impossible to identify, yet everyone knows at once who they belong to. Nine-year-old Michelle Fortier vanished without a trace in 1979, and her fate has remained unknown -- until now.

Stephanie O'Malley grew up in her mother's crumbling trailer listening to stories of Michelle's disappearance, stories she once tried to turn into a podcast without much success. Although Stephanie left Marly fifteen years ago and vowed never to return, she finds herself back with her tempestuous mother Laura, her high school sweetheart Luc, and the entire community in an uproar.

While Stephanie struggles to separate the truth from wild rumors about witchcraft and town-wide conspiracies, Laura is consumed by the strange feeling that all this has happened before. But then a bombshell drops: the body might not be Michelle after all.