On New Year's Eve 2023, Anna, who is with her lover Simon, receives a call from her estranged husband, Dr Marc Honore, who plans to confront the person responsible for ruining his life and killing his patients. Meanwhile, policewoman Juliette struggles to celebrate the night with her daughter, who accuses her of not caring about her late husband. When Marc is found dead in Simon's office, both Juliette and Anna rush to the scene. Later, Juliette and Anna, accompanied by paramedic Cédric, find themselves in an elevator that unexpectedly opens to a bustling lobby filled with revelers celebrating the new year. They realise that they've been transported one year back in time. Cedric and Anna resolve to prevent the patient deaths but Juliette refuses to help, still blaming Marc for her husband's death. As they navigate this altered reality, Cedric inadvertently alters his future. Anna meanwhile tries to avoid meeting and having an affair with Simon. The next day Juliette's husband has a near-fatal heart attack and is rushed to the hospital where Marc operates. Unlike before, however, he does not die. Instead another patient dies later that day.
—smash17