Flashback plot
Elsa Letellier is a forensic scientist with the Lyon police. She chose her career as a tribute to her father, Josselin Letellier, a true police legend, who was mysteriously murdered while performing his duties on his daughter's sixth birthday. Thirty years later, on the evening of her 36th birthday, and just when the case threatens to be closed due to the statute of limitations, Elsa is thrown back to 1994 by an inexplicable phenomenon, just a few months before Josselin's death. After the initial shock and disbelief have subsided, Elsa soon becomes convinced that this return to the past is a divine turn of events: she can prevent her father's death.