Le mystère du lac (2015)

Lise hasn't returned to her small hometown since the tragedy that shattered her teens. Now an urban homicide detective, she is back to care for her Alzheimer's-afflicted mother. But the day she arrives, a neighbor's teenage daughter goes missing, vanished under the exact same circumstances as Lise's two best friends, fifteen years ago. Determined to prevent history from repeating itself, Lise imposes herself on the local cops, led by hard-boiled detective Clovis, to help find the missing girl. Desperate for answers, Lise takes it upon herself to revisit the cold case of her vanished friends and, facing her own painful memories, is confronted by her mother's recollections, including some shocking new revelations. But can the old lady's memory be trusted? Lise gets way more involved than she should as she starts to see how the unsolved mystery has traumatized the town's collective consciousness and how everyone there is a suspect. But as she and Clovis inch closer to the truth, it becomes clear that understanding the past might be the only way to save the day and find the missing girl - if she is still alive.