Totally Killer is like, totally killer.

Forgive the obvious pun, but the film – a mash-up of time travel, horror and poignant family drama mixed lightly with comedy – deftly manages those twists from genre to genre. Totally Killer, streaming on Prime and starring Kiernan Shipka, was directed by Nahnatchka Khan (Always be My Maybe) from a script by David Matalon, Sasha Per-Raver and Jen D’Angelo.

As the movie opens, Jamie (Shipka) is chafing at her parents’ over-protectiveness. She just wants to go to a party with her best friend, but her mom, Pam (Julie Bowen), and dad, Blake (Lochlyn Munro) won’t stop hovering. Jamie reminds her mom that she has been taking self-defense classes since she was 7, but even so, Jamie’s dad drops her off at the party…and waits for her outside.

Pam and Blake have good reason to be afraid, though: back in 1987, when they were in high school, three students were butchered by an assailant known as “The Sweet Sixteen” killer – because he stabbed each victim 16 times. The killing spree ended then, but the town never forgot. (It doesn’t help that true crime podcasters and fans make regular pilgramages to the sites of the murders.

Pam should have been more concerned about herself, though – left alone on Halloween night, she is the slasher’s fourth victim, despite putting up a valiant fight to save herself. This loss leaves Jamie adrift – rejecting both the insincere condolences offered by the school faculty and her father’s attempts to reach her.

Fortunately for Jamie, her best friend Amelia (Kelcey Mawema) is a tinkerer, and has been working on a time machine based on a book of designs her mother Lauren (Troy Leigh-Anne Johnson) developed in high school. What luck! Amelia is entering her project in the science fair, held in the ruins of a once-popular amusement park, if she can only get it to work.

That night, opportunity strikes – and so does the Sweet Sixteen Killer. This time the killer is after Jamie, and as the killer chases her, she ends up in the park’s photo booth, which is where Amelia built her time machine prototype. Thanks to a well-placed blade, the machine powers up and sends Jamie back to 1987.

Jamie quickly realizes where – and when – she is, and wastes no time heading to the town’s only high school. She enrolls with surprising ease, and finds her mom, who is the head of a mean-girls clique called The Mollys, after their fashion inspiration, ’80s icon Molly Ringwald. Besides her mother, Jamie discovers that the other Mollys are the three 1987 victims of the killer – something her mother never told her.

Jamie is faced with two daunting tasks; with no way to prove it, she has to convince everyone in town that the murders that haven’t happened are going to happen. And even trickier, she has to win the friendship of four stuck-up bitches who look down on everyone who isn’t as cool an pretty as they are.

The movie jumps from past to present too, as we see Amelia use old photographs and other artifacts to track Jamie’s progress in the past, and to keep a tally of everything that’s changing due to her action.

How Jamie tries (and often fails) to use her knowledge of the past, and the future, is part of the charm of this movie. The plot zigs and zags enough that it doesn’t step into the familiar footprints of the slasher film, with an ever-increasing body count before one final girl escapes the killer.

Shipka, who was outstanding in Mad Men and The Chilling Adventures of Sabrina, has a natural way with the script’s snappy dialogue, and pivots from angry teen to grief-stricken daughter to intrepid investigator with ease. She elevates an already enjoyable story.

Khan also avoids the obvious ’80s kitsch in favor of more realistic touches. The costumes and set design look as though they came straight out of a contemporary film, such as Sixteen Candles, rather than an attempt to highlight only the most egregious features of the time, like big hair and an excess of neon. The real differences between then and now, which Jamie cannot fail to notice, are the political incorrectness, the casual racism, misogyny, homophobia and fatphobia that are merely background noise to every other character.

The stakes are high for Jamie; she has to save her mother, her father, their future marriage, her friends and herself, unmask the killer, and she has to get back to her own time, despite the fact that the only working time machine she had is back in 2023. How she does it, and the inventive liberties the script takes with familiar film genres, make this a must-watch.