"Totally Killer" spins a lighthearted yet captivating tale, intertwining the celebrated narrative worlds of "Halloween" and "Back to the Future" with a dash of genial self-awareness. Directed by Nahnatchka Khan, acclaimed for her works "Always Be My Maybe" and "Fresh Off the Boat," this inventive genre fusion stirs together a blend of comedy, authentic time-travel science fiction, and horror, albeit the latter perhaps being its least formidable ingredient. Nonetheless, the film's nimbleness and charm pervade its entirety, ensuring a delightful viewer experience.

Much of the film's appeal emanates from the irresistibly charismatic Kiernan Shipka, who deftly delivers brisk dialogue and navigates challenging emotional terrains with skill. The script, penned by David Matalon, Sasha Perl-Raver, and Jen D’Angelo, demands the "Mad Men" alumna transform from a rebellious teenager to a mourning daughter and eventually, a fearless detective, a transition she undertakes seamlessly.

Set on Halloween night in 2023, we meet Shipka’s character, Jamie Hughes, amidst festive preparations with friends. Her mother Pam, portrayed by Julie Bowen, encapsulates maternal anxiety, concerned for Jamie due to a haunting local history: the notorious Sweet Sixteen Killings that plagued their town 35 years prior, when three teenage girls were brutally murdered. However, the plot takes a wild turn when Jamie unintentionally time-travels back to 1987, believing she has the power to thwart the past murders and reshape history.

Yet, it’s not as straightforward as Jamie perceives. A recurring theme throughout "Totally Killer" is the skepticism Jamie encounters when attempting to forewarn others, even from the town’s humorously incompetent sheriff, a role embraced by Khan’s regular, Randall Park. Jamie grapples with culture shock, encountering blatant sexism and pervasive smoking habits, all depicted with just enough unique detail to elevate them beyond mere ‘80s clichés. The film curates a distinctive soundtrack, avoiding typical era hits, instead opting for tracks like Bananarama’s “Venus” and Echo and the Bunnymen’s “The Killing Moon.”

The plot thickens as Jamie mingles with the intended victims and a teenage version of her mother, surprisingly discovering her to be the best friend and alpha of the clique. Olivia Holt's casting as young Pam is spot-on, bearing a striking resemblance to Bowen and skillfully balancing both comedic and malevolent elements of her character. Amidst the backdrop of voluminous hairstyles and Bartles & Jaymes wine coolers, Jamie endeavors to convey future perils based on familiar horror tropes, only to be dismissed.

In an inventive narrative choice, "Totally Killer" intermittently revisits the future—excuse the wordplay—to provide glimpses into present-day events while Jamie navigates 1987, even though a subplot involving a murder podcast arguably lands as predictable and monotonic. Moreover, it explores a scrutinizing perspective on the seclusion intrinsic to small-town existence and the trapping nostalgia of high school peak experiences. The characters possess intimate knowledge of each other, perpetually entwined in a shared history, to which Shipka’s sardonic astonishment serves as a counterbalance, disrupting the illusionary and somewhat romanticized belief of the ‘80s as a superior era.

However, Jamie has little opportunity to ponder—there’s a murderer to prevent. Ironically, this subplot emerges as one of "Totally Killer"’s less intriguing elements. The execution of the slasher scenes lacks precision and the disclosure of the murderer’s identity and intentions pales in comparison to the ingenuity of the resilient final girl who ultimately triumphs, thereby rescuing both the day and the decade.