A teenage girl named Britney and her friend Ella embark on a journey back to 2007 with the goal of preventing Britney's mother, Diane, from facing a tragic fate in the future. The catalyst for their time travel is a watch bestowed upon Britney by an enigmatic woman, enabling both girls to traverse time. They arrive in October 2007, determined to intervene in the notorious Sunnydale murders, which were perpetrated by Murray and Ash. However, they soon discover that the murders are far from over, as a new wave of killings emerges, drawing Britney and Ella into the chaos of the murder spree themselves.